vm/yum-proxy: filter regexp: add missing ^$ marks, remove unneded .* at the beginning
vm/yum-proxy: filter regexp: add missing ^$ marks, remove unneded .* at the beginning

Reported-by: Igor Bukanov <78b6854e22ab09d4ae3dac29b92052963103b33e@mir2.org>

marmarek/qubes-core-admin,woju/qubes-core-admin,marmarek/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin