[BugFix] fix BE crash when http api request for pprof/cmdline (#51077)

Why I'm doing:
BE crash when http api request for pprof/cmdline
curl -s --location-trusted -uroot:"" 'http://127.0.0.1:8040/pprof/cmdline'

What I'm doing:
max field width should be specified in fscanf() so that it does not overflow the buffer

curl -s --location-trusted -uroot:"" 'http://127.0.0.1:8040/pprof/cmdline'
/opensource/deploystarrocks/123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678912345678901234567890123456789012345678901234567890123456/123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678912345678901234567890123456789012345678901234567890123456/123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678912345678901234567890123456789012345678901234567890123456/12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567891234567890123456789012345678

Fixes #51076

Signed-off-by: Rohit Satardekar <[email protected]>
(cherry picked from commit 3543f1d)

be/src/http/action/pprof_actions.cpp

@@ -162,7 +162,7 @@ void CmdlineAction::handle(HttpRequest* req) {
         return;
     }
     char buf[1024];
-    if (fscanf(fp, "%s ", buf) != 1) {
+    if (fscanf(fp, "%1023s ", buf) != 1) {
         strcpy(buf, "read cmdline failed");
     }
     fclose(fp);