Prune data during blocksync

[martintomazic]

Needed for oasisprotocol/oasis-core#6319.

Tested this quickly with state sync and block sync from the genesis (short period). Works.

Seems to also work as a mitigation for badgerDB instances growing too much and not being able to reclaim the disk space: oasisprotocol/oasis-core#6286 (comment).

[martintomazic]

CI failing:

Error: Failed to run: Error: Command failed: /home/runner/golangci-lint-1.64.8-linux-amd64/golangci-lint config verify
jsonschema: "linters-settings" does not validate with "/properties/linters-settings/additionalProperties": additional properties 'golint', 'maligned' not allowed

This properties can be removed, and then we can fix the linting issues. There are also some failing test that I think were there before -> will double check again now that I changed the code.

Not sure we should fix this given this problems are also part of the upstream branch?

Changelog:
Omitted the changelog looking at our previous patches. Once this is merged, we make a new release, and bump the oasis-core part to it, adding a changelog there and impact of the bump (pruning works during block sync)?

Update:
Given that v0.37.15 (upstream) is a longterm support release, I am surprised this was not patched already, like is done for other bugs. Maybe this is not critical or they consider it performance optimization for which you are encouraged to upgrade to a newer version. Possibly given commit name, they are not even aware this was a bug fix... Asking if we should also file an issue for this and aim for this to also get merged upstream eventually...

[kostko]

Upstream is EOL AFAIK.