Re-enable selection UI for TEST_BRANCH

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
Change-Id: I4c8df55eea6cec12c83c27be5e33101098b9327e
diff --git a/mbedtls-release-ci-testing.yaml b/mbedtls-release-ci-testing.yaml
index e22cfd9..8f1701b 100644
--- a/mbedtls-release-ci-testing.yaml
+++ b/mbedtls-release-ci-testing.yaml
@@ -66,11 +66,13 @@
         default: false
         description: Push head to coverity branch, triggering a scan (only done for the development branch)
         name: PUSH_COVERITY
-    - string:
+    - git-parameter:
         name: TEST_BRANCH
         description: Branch or tag in https://github.com/Mbed-TLS/mbedtls-test.git (forks are not supported)
-        default: main
-        trim: true
+        type: PT_BRANCH
+        quickFilterEnabled: true
+        defaultValue: main
+        selectedValue: DEFAULT
     - string:
         name: TEST_PASS_EMAIL_ADDRESS
         description: E-mail addresses (delimited by ,) that a report should be sent to when the test run passes