[ci][tvmbot] Search more users when checking usernames (#12491)

To figure out a user's association with the repo this code before
searched the associations in the repo filtered by the relevant username.
GitHub doesn't return the exact match only though, so we have to instead
collect many results and search through all of them.

Co-authored-by: driazati <[email protected]>

Author: driazati

tests/scripts/github_tvmbot.py

@@ -49,7 +49,7 @@ def to_json_str(obj: Any) -> str:
 COLLABORATORS_QUERY = """
 query ($owner: String!, $name: String!, $user: String!) {
   repository(owner: $owner, name: $name) {
-    collaborators(query: $user, first: 1) {
+    collaborators(query: $user, first: 100) {
       nodes {
         login
       }
@@ -61,7 +61,7 @@ def to_json_str(obj: Any) -> str:
 MENTIONABLE_QUERY = """
 query ($owner: String!, $name: String!, $user: String!) {
   repository(owner: $owner, name: $name) {
-    mentionableUsers(query: $user, first: 1) {
+    mentionableUsers(query: $user, first: 100) {
       nodes {
         login
       }