TT#190151 Replace egrep usage with grep -E

grep 3.8 deprecated support for egrep + fgrep, and now prints a warning on stderr:

| egrep: warning: egrep is obsolescent; using grep -E
| fgrep: warning: fgrep is obsolescent; using grep -F

Change-Id: Iae561f2dc592a24359832a80fde4d6d7cfea97d0

templates/140_apt-keys.yaml.tt2

@@ -5,7 +5,7 @@ command:
     stderr: []
     timeout: 10000
 
-  apt-key list --with-colons | grep '^pub' | cut -d':' -f 5 | egrep -o '.{8}$':
+  apt-key list --with-colons | grep '^pub' | cut -d':' -f 5 | grep -Eo '.{8}$':
     exit-status: 0
     stdout:
     - "!A42C4F2A"