"Better" pattern matching for name of jump VM

The pattern currently used matches also non-exact hits, such as
"jumphost" and "xci-jumphost". This tweak attempts to achieve better
exact word matches. Note: the -w option of grep does not seem to do
the trick as well.

Signed-off-by: Georg Kunz <georg.kunz@est.tech>
Change-Id: I8cb98a5540a41f5e6044efe12584403b7f4398df