Stop using Abseil's definition of RunningOnValgrind().
Stop using Abseil's definition of RunningOnValgrind().

RunningOnValgrind() is defined by a sanitizer, but Abseil defines it
when it not running under a sanitizer. This causes issues with
other libraries that have decided to define it as well.
For example https://github.com/abseil/abseil-cpp/issues/1011

PiperOrigin-RevId: 394483315
Change-Id: I72a9ecef3fb00932e6911bb998f169d28abc5d4b

google/tcmalloc,google/tcmalloc,google/tcmalloc