Add alpha integration tfvars file and update .gitignore to include it

Author: neil-sproston

infrastructure/.gitignore

@@ -20,6 +20,7 @@ crash.*.log
 
 # Allow checked-in preview tfvars containing non-sensitive values and secret references only
 !environments/preview/preview.tfvars
+!environments/preview/alpha-int.tfvars
 
 # Ignore override files as they are usually used to override resources locally and so
 # are not checked in

infrastructure/environments/preview/alpha-int.tfvars

@@ -0,0 +1,11 @@
+provider_url       = "stub"
+provider_mtls_cert = "stub"
+provider_mtls_key  = "stub"
+
+sds_url       = "stub"
+sds_api_token = "stub"
+
+pds_url        = "stub"
+pds_api_token  = "stub"
+pds_api_secret = "stub"
+pds_api_kid    = "stub"