LU-17465 nodemap: change squash default value to 65534

LU-17465 nodemap: change squash default value to 65534

Initially, default values for nodemap.squash_uid/gid/projid were set
to 99, to match user 'nobody'. But on newer systems, nobody has
changed to 65534 and 99 no longer exists.
It is safe to use 65534 in all cases, as even on older systems it
exists and corresponds to 'nfsnobody'.

Test-Parameters: testlist=sanity env=ONLY=432 serverversion=2.15
Test-Parameters: testlist=sanity env=ONLY=432 clientversion=2.15
Test-Parameters: testlist=sanity-quota env=ONLY=75 serverversion=2.15
Test-Parameters: testlist=sanity-quota env=ONLY=75 clientversion=2.15
Test-Parameters: testlist=sanity-selinux env=ONLY=21 serverversion=2.15
Test-Parameters: testlist=sanity-selinux env=ONLY=21 clientversion=2.15
Test-Parameters: testlist=sanity-sec env=ONLY="7 8 9 10 11 12 13 14 15 16 18 19 20 21 22 23 24 25 26 27 32 33 34 35 36 55 61 64" serverversion=2.15
Test-Parameters: testlist=sanity-sec env=ONLY="7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 32 33 34 35 36 55 61 64" clientversion=2.15
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I2e20fda0fdc0d5bfdf964a890bfbd0b54b943cf4
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53802
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>