Workaround compute-sanitizer memcheck bug

[davidwendt]

Description

Provides a workaround for the compute-sanitizer issue described in #15258 causing memcheck failures in nightly builds.
An environment variable is introduced LIBCUDF_MEMCHECK_ENABLED so test code can bypass specific tests that cause the compute-sanitizer error. The env var is set only during memcheck tests since the failure does not occur in normal testing.
The failure only occurs for some int16 or uint16 reduction tests so managing these few tests is reasonable.

Other possible workarounds include

1. Reverting the compute-sanitizer to 11.8
   Using the latest version is more desirable since the fix will likely not be back ported.
2. Adding an exclude filter to the CUB Reduce kernel
   This disables checking for almost all reduction kernels

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[davidwendt]

/merge