Fix merge build fail on docker build

Docker build was failing on git.commit.message.short label
when commit message included double quote mark, which
happens when auto-merging commits.

Quotes around ${git.commit.message.short} were changed
to single quote marks as those are used less frequently.

Issue-ID: DCAEGEN2-2824
Signed-off-by: Remigiusz Janeczek <remigiusz.janeczek@nokia.com>
Change-Id: I1f3622df233ff22a4c312ce1055cf8029880fa09
1 file changed