RUST-2024 Fix serverless CSFLE tests

[abr-egn]

RUST-2024

There were three independent problems happening here:

• The serverless tests and serverless csfle tests were both trying to merge results into results.xml, and the second one would fail because the merge tool (appropriately) won't overwrite a file without an additional flag set. Fixed this by changing the test script to do a rolling merge, which also has the nice effect that our tests don't need to include output file names or an explicit merge step any more.
• Many of the serverless tests were failing because CRYPT_SHARED_LIB_PATH wasn't being set; I tracked this down to a bug in the serverless setup scripts in drivers-evergreen-tools. I've sent https://github.com/mongodb-labs/drivers-evergreen-tools/pull/491 for that and in the meanwhile pointed our testing at my branch with the fix.
• A few of the legacy tests were failing because of CLOUDP-267864; this just needed a test file sync to pick up the serverless skip for those tests.

[abr-egn]

https://spruce.mongodb.com/version/66e06df35524ab00078b4b00/tasks?sorts=STATUS%3AASC%3BBASE_STATUS%3ADESC has a run with these fixes. The Ubuntu 22.04 (ARM64) failures are unrelated, those fail on main as well. I suspect a script breakage.