LU-16314 tests: enable debug_raw_pointers on mount

LU-16314 tests: enable debug_raw_pointers on mount

When the MGS is mounted:
  do_facet mgs "$LCTL set_param -P debug_raw_pointers=Y"

So debug_raw_pointers need only be set once instead of
enabled and distabled for each test.

Switching kptr_restrict for every node on every test (twice)
does not add value when testing on dedicated test VMs.

This adds a KPTR_ON_MOUNT to allow a less restrictive setting
during test-framework setupall()/cleanall().

The initial kptr restrict values are persisted to and restored
from a well-known temporary file $TMP/kptr-$PPID-env

The patch enables KPTR_ON_MOUNT by default.

HPE-bug-id: LUS-10945
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: I4d8975f26e57ea064608663f309400d09406d500
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/54254
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Petros Koutoupis <petros.koutoupis@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>