meta: simplify conditional operations with bb.utils.filter

meta: simplify conditional operations with bb.utils.filter

Some recipes use bb.utils.contains to check for a string inside a
variable, and return the exact same string if true.

This can be simplified by a call to bb.utils.filter, since the result is
the same, and the inline is shorter.

Replace "bb.utils.contains(A, 'a', 'a', '', d)" by "bb.utils.filter(A, 'a', d)".

Signed-off-by: João Marcos Costa <joaomarcos.costa@bootlin.com>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>