Fix Java TLS support bugs, exposed by Kafka TLS

[grcevski]

There were couple of issues here:

1. ReadAdvice was saying it was associating the connection with SSL, but the call to SSLStorage.setConnectionForBuf(bufKey, c); was missing 🤦
2. I had put an optimisation to see if the connection was already associated, but this is wrong, for persistent long lived connections, so I removed the check, now we associate the connection to all buffers.
3. Finally, the matching of the encrypted and unencrypted buffers on the unwrap side of the SSLEngine was done at the wrong place. With TLS 1.3 the decoding can change the original source buffer in place, so the correlation code wasn't working. I fixed this by extracting the key in the Entry method, rather than in the Exit method.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.75%. Comparing base (55f2804) to head (b63d733).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/test/integration/red_test_kafka.go	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1380   +/-   ##
=======================================
  Coverage   43.75%   43.75%           
=======================================
  Files         310      310           
  Lines       33772    33771    -1     
=======================================
  Hits        14777    14777           
+ Misses      18044    18043    -1     
  Partials      951      951           

Flag	Coverage Δ
integration-test	21.59% <ø> (ø)
integration-test-arm	0.00% <ø> (ø)
integration-test-vm-x86_64-5.15.152	0.00% <ø> (ø)
integration-test-vm-x86_64-6.10.6	0.00% <ø> (ø)
k8s-integration-test	2.32% <ø> (+<0.01%)	⬆️
oats-test	0.00% <ø> (ø)
unittests	44.64% <0.00%> (+<0.01%)	⬆️

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[rafaelroquetto]

the nostalgia of reviewing Java code! LGTM!