Bug 23084: Replace grep {^$var$} with grep {$_ eq $var}

Bug 23084: Replace grep {^$var$} with grep {$_ eq $var}

We certainly faced 3 similar bugs due to this syntax: bug 23006, bug
22941 and bug 17526.

To prevent other issues related to this syntax this patch suggests to
replace them all in one go.

Test plan:
Confirm that the 2 syntaxes are similar
Eyeball the patch and confirm that there is no typo!

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>