Revert "[static] Add missing secretKeyRef in GHA setup (#3638)"

This reverts commit 080c7d9.

Signed-off-by: Oriol Muñoz <oriol.munoz@digitalasset.com>

Author: OriolMunoz-da

cluster/pulumi/gha/src/runners.ts

@@ -549,10 +549,8 @@ function installK8sRunnerScaleSet(
                   {
                     name: 'PERFORMANCE_TESTS_DB_PASSWORD',
                     valueFrom: {
-                      secretKeyRef: {
-                        key: 'postgresPassword',
-                        name: performanceTestsDb.secretName,
-                      },
+                      key: 'postgresPassword',
+                      name: performanceTestsDb.secretName,
                     },
                   },
                 ],