force licenses if Kong version >= 3.15

[randmonkey]

What this PR does / why we need it:

Apply licenses in all e2e tests and integration tests if the image of Kong gateway is later than 3.15.0 as it forces a license to accept configuration from KIC.

For the case of retrieving license from Konnect, it enables fetching license from Konnect at the beginning if Kong version >= 3.15.0.

See: https://github.com/Kong/kubernetes-ingress-controller/actions/runs/27670312469

Which issue this PR fixes:

Special notes for your reviewer:

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.4%. Comparing base (c88a091) to head (1904dee).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #7941     +/-   ##
=======================================
- Coverage   78.5%   78.4%   -0.1%     
=======================================
  Files        222     222             
  Lines      20965   20965             
=======================================
- Hits       16464   16447     -17     
- Misses      3460    3475     +15     
- Partials    1041    1043      +2     

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[team-k8s-bot]

E2E (targeted) tests with KIND-based clusters were started at https://github.com/Kong/kubernetes-ingress-controller/actions/runs/27932812971

[tao12345666333]

Test job failed.

=== RUN   TestKongRouterFlavorCompatibility/expressions
    compatibilities_test.go:42: 
        	Error Trace:	/home/runner/work/kubernetes-ingress-controller/kubernetes-ingress-controller/test/e2e/compatibilities_test.go:42
        	Error:      	Received unexpected error:
        	            	could not parse Kong version from TEST_KONG_EFFECTIVE_VERSION or TEST_KONG_TAG: Version string empty
        	Test:       	TestKongRouterFlavorCompatibility/expressions
--- FAIL: TestKongRouterFlavorCompatibility/expressions (0.00s)
=== RUN   TestKongRouterFlavorCompatibility/traditional_compatible
    compatibilities_test.go:42: 
        	Error Trace:	/home/runner/work/kubernetes-ingress-controller/kubernetes-ingress-controller/test/e2e/compatibilities_test.go:42
        	Error:      	Received unexpected error:
        	            	could not parse Kong version from TEST_KONG_EFFECTIVE_VERSION or TEST_KONG_TAG: Version string empty
        	Test:       	TestKongRouterFlavorCompatibility/traditional_compatible
--- FAIL: TestKongRouterFlavorCompatibility/traditional_compatible (0.00s)
=== RUN   TestKongRouterFlavorCompatibility/traditional
    compatibilities_test.go:42: 
        	Error Trace:	/home/runner/work/kubernetes-ingress-controller/kubernetes-ingress-controller/test/e2e/compatibilities_test.go:42
        	Error:      	Received unexpected error:
        	            	could not parse Kong version from TEST_KONG_EFFECTIVE_VERSION or TEST_KONG_TAG: Version string empty
        	Test:       	TestKongRouterFlavorCompatibility/traditional
--- FAIL: TestKongRouterFlavorCompatibility/traditional (0.00s)
    helpers_test.go:116: TestKongRouterFlavorCompatibility failed, dumped diagnostics to /tmp/ktf-diag-3446127965
    helpers_test.go:118: Creating a service to expose admin APIs to dump gateway configuration
    helpers_test.go:118: 
        	Error Trace:	/home/runner/work/kubernetes-ingress-controller/kubernetes-ingress-controller/test/e2e/helpers_test.go:918
        	            				/home/runner/work/kubernetes-ingress-controller/kubernetes-ingress-controller/test/e2e/helpers_test.go:926
        	            				/home/runner/work/kubernetes-ingress-controller/kubernetes-ingress-controller/test/e2e/helpers_test.go:118
        	            				/opt/hostedtoolcache/go/1.25.11/x64/src/testing/testing.go:1308
        	            				/opt/hostedtoolcache/go/1.25.11/x64/src/testing/testing.go:1572
        	            				/opt/hostedtoolcache/go/1.25.11/x64/src/testing/testing.go:1928
        	Error:      	Received unexpected error:
        	            	namespaces "kong" not found
        	Test:       	TestKongRouterFlavorCompatibility
--- FAIL: TestKongRouterFlavorCompatibility (67.67s)
FAIL
FAIL	github.com/kong/kubernetes-ingress-controller/v3/test/e2e	68.019s

https://github.com/Kong/kubernetes-ingress-controller/actions/runs/27932812971/job/82648582407#step:13:279

[tao12345666333]

I will merge this one first, then submit another PR to fix that.