[FRR]Improve handling of ignoring route from default table

[dgsudharsan]

Description

The following PR introduced a fix to ignore route from default table #12018 . Following this another patch was added to ignore error log arising due to the above patch #12912. There are two issues

1. In netlink_route_info_fill should return true on success and false on failure. However the patch [zebra] ignore route from default table #12018 returns zero which is decoded as failure and thus results in error logs

+    if (table_info->table_id == RT_TABLE_DEFAULT) {
+        zfpm_debug("%s: Discard default table route", __func__);
+        return 0;
+    }

2. The code changes to block route from default table is made at a module level (like fpm_netlink) and thus when we are switching to newer module like dplane_fpm the code changes have to be duplicated or might be missed in the migration resulting in issues like [frr-zebra] no valid nexthop error print #18887. The suggestion from FRR community was to make code changes at a higher level in code and not at module level.

Steps to reproduce the issue:

Describe the results you received:

Describe the results you expected:

Output of show version:

(paste your output here)

Output of show techsupport:

(paste your output here or download and attach the file here )

Additional information you deem important (e.g. issue happens only occasionally):

[dgsudharsan]

@StormLiangMS @yxieca @prsunny I have captured some improvements that can be made in the handling of default route table in this ticket. Can you please assign someone as this patch comes from MSFT?

@lguohan for viz.

[prabhataravind]

@StormLiangMS could you please help with this? @lipxu for viz