ci: add ktls + asan build

[lrstewart]

Description of changes:

Most of the ktls code is hit by the standard valgrind and asan tests, but our self-talk tests only run in the specific ktls CI build. For thoroughness, we should probably have at least asan run against the self-talk tests.

While testing, I also found some related issues:

• S2N_KTLS_TESTING_EXPECTED wasn't actually being passed to the final unit test run on the VM. I fixed that, and tested it by making the memory leak I used in my testing only happen if S2N_KTLS_TESTING_EXPECTED is set.
• ASAN needs detect_odr_violation=0 in order not to fail on existing unit tests. I'm not actually sure why detect_odr_violation is enabled by default-- the documentation says that it should be disabled by default, but the documentation might be out of date.

Testing:

I manually kicked off s2nGeneralBatch. You can see the new "ktlsASAN" build passing. It's output says that AddressSanitizer is being configured:

-- Running tests with environment: S2N_DONT_MLOCK=1;S2N_ADDRESS_SANITIZER=1;ASAN_OPTIONS=detect_odr_violation=0
...
1: Test command: /home/codebuild/s2n-tls/build/bin/s2n_3des_test
1: Working Directory: /home/codebuild/s2n-tls/tests/unit
1: Environment variables: 
1:  S2N_DONT_MLOCK=1
1:  S2N_ADDRESS_SANITIZER=1
1:  ASAN_OPTIONS=detect_odr_violation=0

I created a branch with a memory leak that only the ktls build will catch. I manually kicked off a build, and ktlsASAN failed as expected:

170: Running /home/codebuild/s2n-tls/tests/unit/s2n_self_talk_ktls_test.c ... 
170: =================================================================
170: ==17473==ERROR: LeakSanitizer: detected memory leaks
170: 
170: Direct leak of 100 byte(s) in 1 object(s) allocated from:
170:     #0 0x7ffff768d7cf in __interceptor_malloc (/nix/store/5lp5v0sa76mhvc42bdc4z8vxwysp18r9-gcc-11.3.0-lib/lib/libasan.so.6+0xb17cf)
170:     #1 0x41f7bc in s2n_mem_malloc_no_mlock_impl /home/codebuild/s2n-tls/utils/s2n_mem.c:127
170:     #2 0x420377 in s2n_realloc /home/codebuild/s2n-tls/utils/s2n_mem.c:195
170:     #3 0x420a46 in s2n_alloc /home/codebuild/s2n-tls/utils/s2n_mem.c:158
170:     #4 0x405d76 in main /home/codebuild/s2n-tls/tests/unit/s2n_self_talk_ktls_test.c:97
170:     #5 0x7ffff6d1324d in __libc_start_call_main (/nix/store/9xfad3b5z4y00mzmk2wnn4900q0qmxns-glibc-2.35-224/lib/libc.so.6+0x2924d)
170: 
170: SUMMARY: AddressSanitizer: 100 byte(s) leaked in 1 allocation(s).
165/250 Test #170: s2n_self_talk_ktls_test ..........................***Failed    3.51 sec

...

99% tests passed, 1 tests failed out of 250

Label Time Summary:
unit    = 3556.38 sec*proc (250 tests)

Total Test time (real) = 1252.12 sec

The following tests FAILED:
    170 - s2n_self_talk_ktls_test (Failed)

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