fix: reset regex lastIndex to prevent keyword matching failures (#15563)

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## DESCRIBE YOUR PR

This fixes a nuanced regex issue that was creating cases where keywords
were converting correctly in some places but not in other instances on
the same page.

The regex here uses a global flag which is stateful and each regex
`.test()` call inherits lastIndex from the previous call. If lastIndex >
string.length, the test fails and doesn't convert the keyword. This
small update makes sure every `.test()` call starts fresh with lastIndex
= 0 so every string is searched from the beginning.

**PROD: https://docs.sentry.io/product/drains/integration/vercel/
PREVIEW:
https://sentry-docs-git-stale-keyword-fix.sentry.dev/product/drains/integration/vercel/**

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---------

Co-authored-by: getsantry[bot] <66042841+getsantry[bot]@users.noreply.github.com>

Author: jaffrepaul

src/components/codeKeywords/codeKeywords.tsx

@@ -6,7 +6,6 @@ import {KeywordSelector} from './keywordSelector';
 import {OrgAuthTokenCreator} from './orgAuthTokenCreator';
 
 export const KEYWORDS_REGEX = /\b___(?:([A-Z_][A-Z0-9_]*)\.)?([A-Z_][A-Z0-9_]*)___\b/g;
-
 export const ORG_AUTH_TOKEN_REGEX = /___ORG_AUTH_TOKEN___/g;
 
 type ChildrenItem = ReturnType<typeof Children.toArray>[number] | React.ReactNode;
@@ -24,6 +23,11 @@ export function makeKeywordsClickable(children: React.ReactNode) {
       arr.push(updatedChild);
       return arr;
     }
+
+    // Reset regex lastIndex before testing to avoid stale state from previous matches
+    ORG_AUTH_TOKEN_REGEX.lastIndex = 0;
+    KEYWORDS_REGEX.lastIndex = 0;
+
     if (ORG_AUTH_TOKEN_REGEX.test(child)) {
       makeOrgAuthTokenClickable(arr, child);
     } else if (KEYWORDS_REGEX.test(child)) {