ci: Disable downstream jobs temporarily

[steviez]

Problem

I'm attempting to update the version to v3.0.0 in #6425 but running into issues with CI. One such example is here; the problem is:

1. Some stuff in SPL has the following dependency: solana-cli-output = "^2.2.1"
2. solana-cli-output (which lives in Agave) depends on some sdk crates such as solana-clock
3. Prior to this PR, Agave had the versions for sdk crates pinned in the workspace to =2.2.1.
   • That PR relaxed things to ^2.2.1, but didn't land until v2.2.9
   • Due to an unrelated issue, we haven't been able to publish all Agave crates since v2.2.7
4. This means that the latest (2.2.7) solana-cli-output crate has solana-clock pinned to =2.2.1
5. Because of 1. and 4., some SPL stuff inherits solana-clock = "=2.2.1"
6. The Agave master branch has since updated to many of the sdk deps such as solana-clock (now ^2.2.2)
7. The Agave bump to v3.0.0 means solana-cli-output = "^v2.2.1" cannot select 3.0.0 (new major version)

Given 6. and 7., we are unable to select a version for some of these crates as shown by below error from previously linked CI run:

    error: failed to select a version for `solana-hash`.
        ... required by package `solana-cli-output v2.2.1`
        ... which satisfies dependency `solana-cli-output = "^2.2.0"` of package `spl-token-client v0.16.1`
        ... which satisfies dependency `spl-token-client = "^0.16.1"` of package `spl-single-pool-cli v2.0.0 (/home/runner/work/agave/agave/target/downstream-projects/single-pool/clients/cli)`
    versions that meet the requirements `=2.2.1` are: 2.2.1
    
    all possible versions conflict with previously selected packages.
    
      previously selected package `solana-hash v2.3.0`
        ... which satisfies dependency `solana-hash = "^2.3.0"` of package `solana-cli-output v3.0.0 (/home/runner/work/agave/agave/cli-output)`
        ... which satisfies dependency `solana-cli-output = "^3.0.0"` of package `spl-single-pool-cli v2.0.0 (/home/runner/work/agave/agave/target/downstream-projects/single-pool/clients/cli)`

Summary of Changes

Temporarily disable the downstream jobs so that I can merge #6425

I think we'd be able to re-enable these jobs on master once we have a set of v2.3 crates published such that the SPL stuff can get away from the pinned sdk dependencies

[joncinque]

Makes sense to me, thanks!