Use elab2gw, elabgw to reduce axiom usage

[GinoGiotto]

Most changes in this PR are of the same kind of https://github.com/metamath/set.mm/pull/3984 and https://github.com/metamath/set.mm/pull/3991. Specifically:

• Use elab2gw in elpwg -> Drop ax-10, ax-11
• Use elab2gw in eluni -> Drop ax-10, ax-11, ax-12
• Use elab2gw in elintg -> Drop ax-10, ax-11, ax-12
• Use elab2gw in elong -> Drop ax-10, ax-11
• Use elab2gw in isfin2 -> Drop ax-10, ax-11
• Use elabgw in elgch -> Drop ax-10, ax-11
• Use elab2gw in iswun -> Drop ax-10, ax-11
• Use elab2gw in elnpi -> Drop ax-10, ax-11
• Use elab2gw in issal -> Drop ax-10, ax-11

I also removed usage of ax-10, ax-11, ax-12 from opeq1 and opeq2. For these two I did not apply a simple replacement like the revisions above, but I proved them again from scratch. Therefore revision tags and OLD proofs are provided.

All added DV conditions are with dummy variables.

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Results of these changes:

Drop ax-10 from 626 theorems. Drop ax-11 from 520 theorems. Drop ax-12 from 99 theorems.

Full axiom usage here: https://github.com/metamath/set.mm/commit/9566445b0271163393c10cc0837c718f8d8c4c8b