Clean-up unused branches

[lpetre-ulb]

Brief summary of issue

Similarly to what was done for xhal, this issue aims at removing the unused branches from this repository. In this case, the list of branches I'm planning to remove is smaller:

• feature/sca-interface was merged as a backport into develop and release/legacy-1.1 in Feature/sca adc backport #137;
• develop-pre-rebase was created during rebase of develop. Not used since then and no longer useful;
• release/v1.1.X has been replaced with release/legacy-1.1 and should be deleted with a developer-wide announcement.
• feature/templated-rpc-methods is the baseline development branch and could be merged in develop since the minimal RPC porting is done and working and only require thorough tests. The merge should simplify the workflow and prevent any divergence as experienced in the past/other repositories.

[lpetre-ulb]

Closed with #176.