Switch to chromium91 as default webruntime

:Release Notes:
Switch to chromium91 as default webruntime

:Detailed Notes:
This reverts commit 4503f0a1aadd92ccda26b97eacbb4185e5e84642.

When the preferred version is not given, the lastest webruntime
will be the default.

:Testing Performed:
CCC testing

:QA Notes:

:Issues Addressed:
[WRN-6489] Prepare OSE build with chromium91
[WRN-4544] Chromium v91 upgrade for OSE
[WRN-12904] CCC: Switch OSE to chromium91 as default webruntime

Change-Id: I3fe5906cb9b0ace7a24dfd4bcc0cb243e7a27acc

meta-webos/conf/distro/include/webos-preferred-versions.inc

@@ -1,4 +1 @@
-# Copyright (c) 2012-2021 LG Electronics, Inc.
-
-PREFERRED_VERSION_webruntime = "87.%"
-PREFERRED_VERSION_mksnapshot-cross-${TARGET_ARCH} = "87.%"
+# Copyright (c) 2012-2022 LG Electronics, Inc.