ci/papr: Drop required commit status context

This was useful in combination with Homu since it only had to watch one
context. Since we're not using Homu anymore (and Tide instead looks at
all statuses by default), let's just drop it. This brings down the
number of statuses on PRs by one more (and so one less context to
override when needed).

Relatedly, also just test on `master` now.

.papr.yml

@@ -1,5 +1,4 @@
 context: f29-primary
-inherit: true
 
 cluster:
   hosts:
@@ -34,11 +33,6 @@ artifacts:
 
 ---
 
-branches:
-  - master
-  - auto
-  - try
-
 # NB: when bumping 29 here, also bump compose script
 
 context: f29-compose1
@@ -47,8 +41,6 @@ build: false
 
 timeout: 35m
 
-required: true
-
 # This test case wants an "unprivileged container with bubblewrap",
 # which we don't have right now; so just provision a VM and do a
 # docker --privileged run.