BattleSearch: Replace lookahead with union (#10679)

PCRE lookahead was causing the regex to be pathologically slow.

server/chat-plugins/battlesearch.ts

@@ -46,10 +46,12 @@ export async function runBattleSearch(userids: ID[], month: string, tierid: ID,
 	if (useRipgrep) {
 		// Matches non-word (including _ which counts as a word) characters between letters/numbers
 		// in a user's name so the userid can case-insensitively be matched to the name.
-		const regexString = userids.map(id => `(?=.*?("p(1|2)":"${[...id].join('[^a-zA-Z0-9]*')}[^a-zA-Z0-9]*"))`).join('');
+		// We want to be order-insensitive for the player IDs. This union is much cheaper than using PCRE.
+		const userUnion = userids.map(id => `${[...id].join('[^a-zA-Z0-9]*')}[^a-zA-Z0-9]*`).join('|');
+		const regexString = userids.map(id => `(.*?("p(1|2)":"(${userUnion})"))`).join('');
 		let output;
 		try {
-			output = await ProcessManager.exec(['rg', '-i', regexString, '--no-line-number', '-P', '-tjson', ...files]);
+			output = await ProcessManager.exec(['rg', '-i', regexString, '--no-line-number', '-tjson', ...files]);
 		} catch {
 			return results;
 		}