test: do not check error messages meant for humans (#540)

##### SUMMARY

Reduce tests flakiness, as human error messages may change over time.

tests/integration/targets/server/tasks/test_basic.yml

@@ -316,7 +316,6 @@
     that:
       - result is failed
       - result.failure.code == "protected"
-      - result.failure.message == "server deletion is protected"
 
 - name: test rebuild server fails if it is protected
   hetzner.hcloud.server:
@@ -330,7 +329,6 @@
     that:
       - result is failed
       - result.failure.code == "protected"
-      - result.failure.message == "server rebuild is protected"
 
 - name: test remove server protection
   hetzner.hcloud.server:
@@ -588,7 +586,6 @@
     that:
       - result is failed
       - result.failure.code == "protected"
-      - result.failure.message == "server deletion is protected"
 
 - name: remove protection from server
   hetzner.hcloud.server:

tests/integration/targets/server/tasks/test_firewalls.yml

@@ -14,7 +14,6 @@
     that:
       - result is failed
       - result.failure.code == "not_found"
-      - result.failure.message == "firewall not-existing was not found"
 
 - name: setup create firewalls
   hetzner.hcloud.firewall:

tests/integration/targets/server/tasks/test_validation.yml

@@ -35,7 +35,6 @@
     that:
       - result is failed
       - result.failure.code == "not_found"
-      - result.failure.message == "server_type not-existing-server-type was not found"
 
 - name: test create server with not existing image
   hetzner.hcloud.server:
@@ -50,4 +49,3 @@
     that:
       - result is failed
       - result.failure.code == "not_found"
-      - result.failure.message == "Image my-not-existing-image-20.04 was not found"