all: remove osaka and bpo override flags

[lightclient]

Currently --override.osaka doesn't work because it only overrides with the provided time, but does not provide a blob schedule. Since the blob schedule isn't provided on any network yet, it will fail to start. Even after we add the Osaka blob schedule to the default networks, it usefulness is very limited since 1) it alone cannot change the max or target for the fork and 2) there are several BPOs scheduled alongside Osaka with their own max and targets - none of which can be overridden yet.

For those reasons, I propose removing the OverrideOsaka flag and pursue a complete / future-proof solution such as #32556.

[rjl493456442]

To clarify, the current override mechanism is limited to modifying fork timestamps
and cannot change other fork parameters.

Given that the primary use case is expected to be timestamp adjustment (e.g.,
manually delay a fork activation), I think we should keep this mechanism for now.
A more comprehensive solution can be introduced later for replacement?

[lightclient]

That's correct. But even just limiting to the timestamp, we don't have any of the 5 BPOs implemented with an override. And each would require we add the blob schedule somehow when we override. This also currently isn't implemented.

So IMO if we keep the Osaka override we have some additional things to add and we give ourselves permanent responsibility of churning these override flags. It made sense to me when it was occasional and one at a time, but now I think #32556 is a better solution going forward.

[lightclient]

Updated to remove BPO flags also :)