Fix running complement.sh script. (#11368)

By reverting changes from #11166 in this script. Specifically commit
13f084eb.

changelog.d/11368.misc

+Fix running `scripts-dev/complement.sh`, which was broken in v1.47.0rc1.

scripts-dev/complement.sh

@@ -24,7 +24,7 @@
 set -e
 
 # Change to the repository root
-cd "$(dirname "$0")/.."
+cd "$(dirname $0)/.."
 
 # Check for a user-specified Complement checkout
 if [[ -z "$COMPLEMENT_DIR" ]]; then
@@ -61,8 +61,8 @@ cd "$COMPLEMENT_DIR"
 EXTRA_COMPLEMENT_ARGS=""
 if [[ -n "$1" ]]; then
   # A test name regex has been set, supply it to Complement
-  EXTRA_COMPLEMENT_ARGS=(-run "$1")
+  EXTRA_COMPLEMENT_ARGS+="-run $1 "
 fi
 
 # Run the tests!
-go test -v -tags synapse_blacklist,msc2946,msc3083,msc2403,msc2716 -count=1 "${EXTRA_COMPLEMENT_ARGS[@]}" ./tests/...
+go test -v -tags synapse_blacklist,msc2946,msc3083,msc2403,msc2716 -count=1 $EXTRA_COMPLEMENT_ARGS ./tests/...