fix: use "true" instead of "1" for E2E_COLLECT_COVERAGE env var

For consistency with other boolean env vars in the codebase (like
E2E_NIGHTLY_MODE, USE_NEW_FRONTEND_SYSTEM), change from checking
"1" to checking "true".

Updated in:
- src/playwright/fixtures/test.ts (_coverageCollector fixture)
- src/utils/plugin-metadata.ts (coverage image swap)
- docs/changelog.md (documentation)

Addresses: #95 (comment)

Author: gustavolira

src/utils/plugin-metadata.ts

@@ -489,7 +489,7 @@ async function resolvePluginPackages(
         const prUrl = prOciUrls.get(displayName);
         if (prUrl) {
           const usesCoverage =
-            process.env.E2E_COLLECT_COVERAGE === "1" &&
+            process.env.E2E_COLLECT_COVERAGE === "true" &&
             metadata.role === "frontend-plugin";
           const resolved = usesCoverage
             ? prUrl.replace(/(:[^!]+)/, "$1__coverage")