bgpd: adding flog_err for long cli

Adding flog_err to log the error when
the cli entered by user exceeds 8k limit

Testing:
Logging below error for long cli string:
2024-10-22T05:18:02.991041+00:00 leaf22 bgpd[416151]: [VRACB-29FDG]
[EC 100663304] Command too long: 6402:429496616 429496402:429496402:429496617
429496402:429496402:429496618 429496402:429496402:429496619
429496402:429496402:429496620 429496402:429496402:429496621

Ticket: #4127865

Signed-off-by: Manpreet Kaur <[email protected]>

Author: Manpreet-k0

lib/vty.c

@@ -2423,6 +2423,7 @@ static void vtysh_read(struct event *event)
 		/* Clear command line buffer. */
 		vty->cp = vty->length = 0;
 		vty_clear_buf(vty);
+		flog_err(EC_LIB_VTY, "Command too long: %.*s", nbytes, buf);
 		vty_out(vty, "%% Command is too long.\n");
 	} else {
 		for (p = buf; p < buf + nbytes; p++) {