Bridge: fix zombienet tests (paritytech#4367)

Due to recent bump of Rococo/Westend versions + the fact that
paritytech/parity-bridges-common#2894 has
finally reached this repo, tests now fail, because we've started
checking all client versions (even source) unless we specify
`--source-version-mode Auto` in CLI arguments. This looks like an
overkill, but all those version checks will be fixed by
paritytech#4256, so now it makes
sense just to add this CLI option. We also need to propagate it to
running relays eventually.

bridges/testing/environments/rococo-westend/bridges_rococo_westend.sh

@@ -177,6 +177,7 @@ function run_finality_relay() {
  --only-free-headers \
  --source-host localhost \
  --source-port 9942 \
+ --source-version-mode Auto \
  --target-host localhost \
  --target-port 8945 \
  --target-version-mode Auto \
@@ -188,6 +189,7 @@ function run_finality_relay() {
  --only-free-headers \
  --source-host localhost \
  --source-port 9945 \
+ --source-version-mode Auto \
  --target-host localhost \
  --target-port 8943 \
  --target-version-mode Auto \
@@ -203,6 +205,7 @@ function run_parachains_relay() {
  --only-free-headers \
  --source-host localhost \
  --source-port 9942 \
+ --source-version-mode Auto \
  --target-host localhost \
  --target-port 8945 \
  --target-version-mode Auto \
@@ -214,6 +217,7 @@ function run_parachains_relay() {
  --only-free-headers \
  --source-host localhost \
  --source-port 9945 \
+ --source-version-mode Auto \
  --target-host localhost \
  --target-port 8943 \
  --target-version-mode Auto \