Remove letstest on Amazon Linux

tests/letstest/auto_targets.yaml

@@ -57,10 +57,3 @@ targets:
     type: centos
     virt: hvm
     user: centos
-  #-----------------------------------------------------------------------------
-  # Amazon Linux
-  - ami: ami-0ff8a91507f77f867
-    name: amazon
-    type: centos
-    virt: hvm
-    user: ec2-user

tests/letstest/scripts/test_leauto_upgrades.sh

@@ -156,7 +156,7 @@ fi
 # Finally, we check if our local server received more requests. Over time,
 # we'll move more and more OSes into this case until it this is the expected
 # behavior on all systems.
-if [ -f /etc/issue ] && grep -iq "Amazon Linux" /etc/issue; then
+if [ -f /etc/redhat-release ]; then
     if ! diff "$LOG_FILE" "$PREVIOUS_LOG_FILE" ; then
         echo our local server received unexpected requests
         exit 1