Always use SSH checkouts in test jobs

This allows us to bypass Github rate-limits on anonymous checkouts.

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
Change-Id: I353ef36a955e29b9d7c06cad1e77755f8ddceed0
diff --git a/mbedtls-release-ci-testing.yaml b/mbedtls-release-ci-testing.yaml
index 24df334..359d2fc 100644
--- a/mbedtls-release-ci-testing.yaml
+++ b/mbedtls-release-ci-testing.yaml
@@ -5,7 +5,7 @@
     name: mbedtls-release-ci-testing
     parameters:
     - string:
-        default: https://github.com/Mbed-TLS/mbedtls.git
+        default: ssh://git@github.com/Mbed-TLS/mbedtls.git
         description: Enter mbed TLS repo/fork
         name: MBED_TLS_REPO
         trim: 'true'
@@ -67,7 +67,7 @@
         name: MBED_CRYPTO_BRANCH
         trim: 'true'
     - string:
-        default: https://github.com/ARMmbed/mbed-os.git
+        default: ssh://git@github.com/ARMmbed/mbed-os.git
         description: Enter the Mbed OS repo or fork
         name: MBED_OS_REPO
         trim: 'true'
@@ -80,7 +80,7 @@
         name: MBED_OS_BRANCH
         trim: 'true'
     - string:
-        default: https://github.com/ARMmbed/mbed-os-example-tls.git
+        default: ssh://git@github.com/ARMmbed/mbed-os-example-tls.git
         description: |-
           Enter the Mbed OS examples repo or fork.
 
@@ -122,7 +122,8 @@
       - git:
           branches:
           - ${TEST_BRANCH}
-          url: https://github.com/Mbed-TLS/mbedtls-test.git
+          credentials-id: mbedtls-github-ssh
+          url: ssh://git@github.com/Mbed-TLS/mbedtls-test.git
       script-path: vars/mbedtls-release-Jenkinsfile
     project-type: pipeline
     properties: