Bug 1655921 - Stop running `make check` in valgrind builds. r=froydnj

This has the side effect of not initializing fontconfig before the
valgrind test itself runs, which changes the code path leading to
`FcConfigAddDirList`, which eventually leads to suppressed leaks.
Those leaks are then not discarded because the caller doesn't match what
is in the suppression file anymore, so we remove the caller.

Differential Revision: https://phabricator.services.mozilla.com/D85353

browser/config/mozconfigs/linux64/valgrind

@@ -1,3 +1,5 @@
+MOZ_AUTOMATION_CHECK=0
+
 . $topsrcdir/browser/config/mozconfigs/linux64/nightly
 
 ac_add_options --enable-valgrind

build/valgrind/x86_64-pc-linux-gnu.sup

@@ -57,7 +57,6 @@
    fun:FcDirCacheWrite
    fun:FcDirCacheScan
    fun:FcConfigAddDirList
-   fun:FcConfigAppFontAddDir
    ...
 }
 {
@@ -68,7 +67,6 @@
    fun:FcDirScanConfig
    fun:FcDirCacheScan
    fun:FcConfigAddDirList
-   fun:FcConfigAppFontAddDir
    ...
 }
 {
@@ -80,7 +78,6 @@
    fun:FcDirScanConfig
    fun:FcDirCacheScan
    fun:FcConfigAddDirList
-   fun:FcConfigAppFontAddDir
    ...
 }
 {
@@ -92,7 +89,6 @@
    obj:/usr/lib/x86_64-linux-gnu/libfontconfig.so.1.5.0
    fun:FcDirCacheScan
    fun:FcConfigAddDirList
-   fun:FcConfigAppFontAddDir
    ...
 }
 # Leaks due to either Gtk+3 or cairo, but Gecko is not directly involved with