Correctly use $wgFeedLimit in page history feed

The previous behavior enforced a minimal maximum of 10, even if
$wgFeedLimit was set to a lower value.

Also grepped everything for $wgFeedLimit and fixed all other
error-prone (but correct) uses.

Bug: 50886
Change-Id: Ia81bbadfcf4270b0f932b543265ca37f364530f3
Merge "Correctly use $wgFeedLimit in page history feed"