test: expand s2n_record_read testing to both TLS.13 and TLS.12

[toidiu]

Description of changes:

A test in s2n_record_read_test.c passes for TLS1.2 but fails when TLS1.3 protocol is negotiated. This is unexpected since record reading behavior should be protocol independent.

The test "corrupts" a payload by modifying the ContentType (first byte) and expects a decryption error. However, this doesn't work for TLS1.2 since ConentType is not used in decryption in TLS1.3.

The fix in this PR is to instead corrupt the 6th byte (the encrypted data), which should result in an error for both TLS1.2 and TLS1.3.

Testing:

Expand test to both the TLS1.2 andTLS1.3 protocol.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[lrstewart]

Nit: You might want to assert that you really are negotiating the version you expect, so that you're not writing another test that will have an unpredictable version if assumptions change :) Which would mean you'd probably want something like this instead:

struct {
    const char *policy;
    uint8_t version;
} test_cases[] = {
    { .policy = 20240503, .version = S2N_TLS13 }
}

[lrstewart]

Would the last byte be simpler / more obvious?

[toidiu]

Skipping the last byte does work but I prefer skipping the header len amount since that is the reason why this currently doesnt work.

// skipping last byte tested via

int last_byte = s2n_stuffer_data_available(&invalidation_stuffer) - 1;    
...
EXPECT_SUCCESS(s2n_stuffer_skip_read(&invalidation_stuffer, last_byte));