fix(tests): overwrite an old enterprise image in ktf

[pmalek]

What this PR does / why we need it:

This fixes a problem where we skip tests that we wouldn't like to skip, e.g. https://github.com/Kong/kubernetes-ingress-controller/actions/runs/4086412787/jobs/7045676471#step:7:15296

=== Skipped
=== SKIP: test/integration TestIngressRegexMatchPath (0.00s)
    ingress_regex_match_test.go:32: regex prefixes are only relevant for Kong 3.0+

=== SKIP: test/integration TestIngressRegexMatchHeader (0.00s)
    ingress_regex_match_test.go:186: regex prefixes are only relevant for Kong 3.0+

=== SKIP: test/integration TestIngressClassRegexToggle (1.00s)
    ingress_test.go:565: legacy regex detection is only relevant for Kong 3.0+

=== SKIP: test/integration TestIngressRegexPrefix (0.00s)
    ingress_test.go:698: regex prefixes are only relevant for Kong 3.0+

=== SKIP: test/integration TestIngressRecoverFromInvalidPath (0.00s)
    ingress_test.go:861: the case TestIngressRecoverFromInvalidPath should be run separately; please set TEST_RUN_INVALID_CONFIG_CASES to true to run this case

=== SKIP: test/integration TestPluginOrdering (1.00s)
    plugin_test.go:207: plugin ordering requires Kong Enterprise 3.0+

Related issues in ktf: Kong/kubernetes-testing-framework#542

In essence then, this PR bumps enterprise image that we test from 2.7.0.0-alpine to 3.1.1.3-alpine

Special notes for your reviewer:

This adds a TODO which contains several options on how to approach this problem. PTAL

[codecov]

Codecov Report

Base: 73.9% // Head: 73.8% // Decreases project coverage by -0.1% ⚠️

Coverage data is based on head (e5004f2) compared to base (99768a5).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #3486     +/-   ##
=======================================
- Coverage   73.9%   73.8%   -0.1%     
=======================================
  Files        118     118             
  Lines      13990   13990             
=======================================
- Hits       10348   10338     -10     
- Misses      2982    2990      +8     
- Partials     660     662      +2     

Impacted Files	Coverage Δ
...nternal/controllers/gateway/tlsroute_controller.go	71.4% <0.0%> (-2.1%)	⬇️
...nternal/controllers/gateway/tcproute_controller.go	70.0% <0.0%> (-2.0%)	⬇️
internal/dataplane/parser/parser.go	91.5% <0.0%> (+0.8%)	⬆️

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[pmalek]

Only 1 test (expected) skipped:

=== Skipped
=== SKIP: test/integration TestIngressRecoverFromInvalidPath (0.00s)
    ingress_test.go:861: the case TestIngressRecoverFromInvalidPath should be run separately; please set TEST_RUN_INVALID_CONFIG_CASES to true to run this case

DONE 94 tests, 1 skipped in 1637.925s