services/horizon: change configuration of SKIP_TXMETA in puppet to true

[mollykarcher]

What problem does your feature solve?

We announced back in January that we would be sunsetting txmeta from Horizon, in anticipation of a potential for a large increase in data size following the launch of Soroban. The ecosystem alternative should they need access to txmeta is to get it from RPC's getTransactions endpoint, and this has been available since 21.3.0 (~mid June).

What would you like to see?

Change the default for the SKIP_TXMETA flag to true, so that txmeta is no longer returned by Horizon by default.

What alternatives are there?

• Leave the default as false and simply set the config to true on SDF's Horizon deployment. Even though this isn't what we had originally planned, I think that given we haven't seen the explosion in data size due to Soroban that was anticipated, this might be the better option to go with for now, given it's less disruptive overall. And it still de-risks us from our deployment's perspective, since we don't need to store/service it on ours. Open to thoughts here.

[mollykarcher]

Note that we decided on the "alternative approach" described in the description. Changed the title of ticket to match