CDRIVER-5901 set cryptSharedLibPath if not present

[kevinAlbs]

Summary

Apply a cryptSharedLibPath to the unified test runner.

Tested by this patch build.

Background

This applies a consistent search path for crypt_shared. Using a consistent path may avoid triggering an error from libmongocrypt. I expect this did not trigger an error from libmongocrypt since tests were not run concurrently (only one crypt_shared was loaded in process at a time).

A previous task logged different loaded paths:

Opened CSFLE dynamic library [/data/mci/81d2c540daaa5d945ee007f03d0acce5/drivers-evergreen-tools/mongo_crypt_v1.so]
...
Opened CSFLE dynamic library [mongo_crypt_v1.so]

With these changes, a task now consistently logs:

Opened CSFLE dynamic library [/data/mci/37e16be5448147f44bc1d84dbffde64e/drivers-evergreen-tools/mongo_crypt_v1.so]