fix: relative path when on gha

[meyer9]

Description

Fixes fetching metadata and test runs on GHA. Previously, we used a relative path, so requesting output/metadata.json would resolve to https://base.github.io/benchmark/output/metadata.json when requested from https://base.github.io/benchmark.

The previous change added a leading / to the beginning of the path, so it was not resolving the relative path correctly. Now, we ensure the base url has a trailing / and remove the leading / from request URLs so the static site is portable to any path.

Testing

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1