Enable shallow clones and lightweight checkouts everywhere

This brings us in line with the internal CI

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
Change-Id: Iddd1758be9f2b36b4bb79be36942f6fd56faf182
diff --git a/mbed-tls-nightly-tests.yaml b/mbed-tls-nightly-tests.yaml
index f8c2daa..b27c730 100644
--- a/mbed-tls-nightly-tests.yaml
+++ b/mbed-tls-nightly-tests.yaml
@@ -72,6 +72,9 @@
           - main
           credentials-id: mbedtls-github-ssh
           url: ssh://git@github.com/Mbed-TLS/mbedtls-test.git
+          shallow-clone: true
+          do-not-fetch-tags: true
+          honor-refspec: true
       script-path: vars/mbedtls-release-Jenkinsfile
     project-type: pipeline
     properties: