add daily github actions with libc malloc and valgrind

* fix memlry leaks with diskless replica short read.
* fix a few timing issues with valgrind runs
* fix issue with valgrind and watchdog schedule signal

about the valgrind WD issue:
the stack trace test in logging.tcl, has issues with valgrind:
==28808== Can't extend stack to 0x1ffeffdb38 during signal delivery for thread 1:
==28808==   too small or bad protection modes

it seems to be some valgrind bug with SA_ONSTACK.
SA_ONSTACK seems unneeded since WD is not recursive (SA_NODEFER was removed),
also, not sure if it's even valid without a call to sigaltstack()
