Remove old experiment configs for powers-of-two-below-64, which has launched already.
Remove old experiment configs for powers-of-two-below-64, which has launched already.

PiperOrigin-RevId: 480412877
Change-Id: I0b1580145cf6fa416b6e62aa8f7e8dec3690eac6

google/tcmalloc,google/tcmalloc,google/tcmalloc