TT#37257 Fix unnecessary subshell call and remove 'shellcheck disable'

It was initially introduced in the commit:

> commit 7d422b7878
> Author: Victor Seva <vseva@sipwise.com>
> Date:   Fri Aug 22 17:03:39 2014 +0200
>
> MT#8763 check for .git before running the services
>
> On a multi directory config, the services depends on git. Check
> first if the git repository exists and warn about it

The subshell here was necessary to isolate 'cd $dir' call.
In the same time the "proper" bash way is to use pushd/popd.

For the history, 'shellcheck disable' was muting the warning:
> This only exits the subshell caused by the (..) group. [SC2106]

Change-Id: I3546fa9615858dbbc4c0f91d74de003e22837d55

scripts/services

@@ -132,13 +132,11 @@ TMPFILE="$(mktemp)"
 log_debug "TMPFILE = $TMPFILE"
 
 for dir in ${CONFIG_POOL} ; do
-  #shellcheck disable=SC2106
-  (
   if ! [[ "${dir}" =~ ^/ ]] ; then
     log_error "${dir} is not an absolute path"
     continue
   fi
-  cd "${dir}"
+  pushd "${dir}" >/dev/null
   if [ ! -d .git ] ; then
     log_info "$dir has no support of .services"
     continue
@@ -152,7 +150,7 @@ for dir in ${CONFIG_POOL} ; do
       unifyer "${SERVICES_POOL_BASE}/${dir}/$(dirname "$file")/ngcpcfg.services"
     fi
   done
-  )
+  popd >/dev/null
 done
 
 if ! [ -s "$TMPFILE" ] ; then