Cleanup bootrap5 specific branch of the homepage repository

[GeorgianaElena]

Context

Because JuptyerHub5 comes with bootstrap5, as part of #5209 we had to upgrade the hub homepage UI and make it compatible with this version of the library.

This has resulted in #5316 which means that each of the branches that we're using with our JupyterHub 4 setup now have a bootstrap5 counterpart.

Apart from this, two community maintained homepages, veda and ghg, have been ported onto a 2i2c specific branch until the upgrade happens.

Once all the hubs have been upgraded and #5292 has been merged, we should clean-up these branches.

Tasks

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1. merge all bootrap5 prefixed branches of https://github.com/2i2c-org/default-hub-homepage have been into their original branch
2. update the hubs config so that they use the non bootstrap5 prefixed branches
3. PRs have been created against the orginal veda and ghg repositories (https://github.com/US-GHG-Center/ghgc-hub-homepage (master and staging branches) and https://github.com/NASA-IMPACT/veda-hub-homepage (master and staging branches)) with the bootstrap changes and the hubs use those again.
4. delete bootrap5 prefixed branches from https://github.com/2i2c-org/default-hub-homepage

Definition of Done

• the hubs use the original non bootstrap5 prefixed branches