archive/tar: perform test for hole-detection on specific builders

The test for hole-detection is heavily dependent on whether the
OS and underlying FS provides support for it.
Even on Linux, which has support for SEEK_HOLE and SEEK_DATA,
the underlying filesystem may not have support for it.
In order to avoid an ever-changing game of whack-a-mole,
we whitelist the specific builders that we expect the test to pass on.

Updates #21964

Change-Id: I7334e8532c96cc346ea83aabbb81b719685ad7e5
Reviewed-on: https://go-review.googlesource.com/65270


Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>