Update soroban xdr

[paulbellamy]

PR Checklist

PR Structure

• This PR has reasonably narrow scope (if not, break it down into smaller PRs).
• This PR avoids mixing refactoring changes with feature changes (split into two PRs
  otherwise).
• This PR's title starts with name of package that is most changed in the PR, ex.
  services/friendbot, or all or doc if the changes are broad or impact many
  packages.

Thoroughness

• This PR adds tests for the most critical parts of the new functionality or fixes.
• I've updated any docs (developer docs, .md
  files, etc... affected by this change). Take a look in the docs folder for a given service,
  like this one.

Release planning

• I've updated the relevant CHANGELOG (here for Horizon) if
  needed with deprecations, added features, breaking changes, and DB schema changes.
• I've decided if this PR requires a new major/minor version according to
  semver, or if it's mainly a patch change. The PR is targeted at the next
  release branch if it's not a patch change.

What

Updated xdr to commit 026c9cd074bdb28ddde8ee52f2a4502d9e518a09

Had to change a couple small implementations to adapt.

Why

OperationEvents change is required for #4694

We probably want to update it for the release anyway.

Todo

• TBD still if we want to include the ScBigInt removal xdr change in this release or delay that until next.
• Handle wasm code/wasm id changes
• Handle InvokeHostFunctionOp.Parameters removal

[2opremio]

The integration tests should be fixed except for TestInvokeHostFunctionInvokeStatelessContractFn() which requires updating https://github.com/stellar/go/blob/soroban-xdr-next/services/horizon/internal/integration/testdata/test_add_u64.wasm for which I can't find the source code.

I am also going to disable the Soroban RPC tests in this repo, because the fixes/updates required are at the new tools repo ( stellar/stellar-cli#274 )

[paulbellamy]

We should probably have these built somewhere official, not on just our personal dockerhubs... But that's not really an issue with this PR.

[2opremio]

Yeah, I didn't find a better way since the docker repo where builds are put is internal.

[paulbellamy]

LGTM, but I can't approve it as I'm an author 😂

[2opremio]

It seems like the apt repo is acting up:

Could not connect to azure.archive.ubuntu.com:80 (52.147.219.192), connection timed out