bootstrap-tarballs: Use rm -f instead of || true

The use of `|| true` will cause an error message to be printed by `rm`
which may lead QA personnel to believe that there is something wrong
while there is not. -f will simply ignore nonexistent files.

```
rm: cannot remove 'nosuchfile': No such file or directory
```

Signed-off-by: Lars Erik Wik <lars.erik.wik@northern.tech>

Author: larsewi

build-scripts/bootstrap-tarballs

@@ -56,7 +56,7 @@ set -e
 
 # Build tarball from core repository
 cd "$BASEDIR"/core
-rm cfengine-3.*.tar.gz || true
+rm -f cfengine-3.*.tar.gz
 git rev-parse HEAD > "$BASEDIR"/output/core-commitID
 # Configure in order to run "make dist", deleted later.
 ./configure -C
@@ -66,7 +66,7 @@ make distclean
 
 # Build tarballs from masterfiles repository
 cd "$BASEDIR"/masterfiles
-rm cfengine-masterfiles*.tar.gz || true
+rm -f cfengine-masterfiles*.tar.gz
 git rev-parse HEAD > "$BASEDIR"/output/masterfiles-commitID
 # Configure in order to run "make dist", deleted later.
 ./configure