Reduce GitHub API usage by trusting nobody

Checking for collaborator permissions requires GitHub API calls, and we
never change the Jenkinsfile in the repos, so fetch the upstream
Jenkinsfile unconditionally.

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
Change-Id: Idfee2992c899925fda0b85b191dd501ef62031c7
diff --git a/mbed-tls-pr-head.yaml b/mbed-tls-pr-head.yaml
index 630790e..a55d347 100644
--- a/mbed-tls-pr-head.yaml
+++ b/mbed-tls-pr-head.yaml
@@ -36,7 +36,7 @@
         repo: mbedtls
         branch-discovery: no-pr
         discover-pr-forks-strategy: both
-        discover-pr-forks-trust: permission
+        discover-pr-forks-trust: nobody
         discover-pr-origin: both
         head-filter-regex: '(?!PR-7959-head$)PR-\d+-head|gh-readonly-queue/(?!dev/bensze01/merge-queue-test/).*'
         status-checks:
diff --git a/mbed-tls-pr-merge.yaml b/mbed-tls-pr-merge.yaml
index a9fd447..692038f 100644
--- a/mbed-tls-pr-merge.yaml
+++ b/mbed-tls-pr-merge.yaml
@@ -36,7 +36,7 @@
         repo: mbedtls
         branch-discovery: no-pr
         discover-pr-forks-strategy: both
-        discover-pr-forks-trust: permission
+        discover-pr-forks-trust: nobody
         discover-pr-origin: both
         head-filter-regex: '(?!PR-7959-merge$)PR-\d+-merge'
         status-checks:
diff --git a/mbed-tls-restricted-pr-ci-testing.yaml b/mbed-tls-restricted-pr-ci-testing.yaml
index 2890767..b05b97b 100644
--- a/mbed-tls-restricted-pr-ci-testing.yaml
+++ b/mbed-tls-restricted-pr-ci-testing.yaml
@@ -53,7 +53,7 @@
         branch-discovery: all
         discover-pr-origin: both
         discover-pr-forks-strategy: both
-        discover-pr-forks-trust: permission
+        discover-pr-forks-trust: nobody
         head-filter-regex: 'PR-7959-(head|merge)|gh-readonly-queue/dev/bensze01/merge-queue-test/.*'
         status-checks:
           skip: true
diff --git a/mbed-tls-restricted-pr.yaml b/mbed-tls-restricted-pr.yaml
index 80e8042..b71dd5c 100644
--- a/mbed-tls-restricted-pr.yaml
+++ b/mbed-tls-restricted-pr.yaml
@@ -35,7 +35,7 @@
         repo: mbedtls-restricted
         branch-discovery: no-pr
         discover-pr-forks-strategy: both
-        discover-pr-forks-trust: permission
+        discover-pr-forks-trust: nobody
         discover-pr-origin: both
         head-filter-regex: '(?!^PR-(758|759|806|850|906|916|919)-(merge|head)$)(PR-\d+-(merge|head))'
         status-checks: