Merge #1400

1400: Remove incorrect hydrostatic_implicit.jl test r=charleskawczynski a=charleskawczynski

I went to convert `hydrostatic_implicit.jl` to use ClimaTimesteppers, and `@dennisYatunin` and I discovered a bug that renders the test useless:

```julia
function linsolve!(::Type{Val{:init}}, f, u0; kwargs...)
    function _linsolve!(x, A, b, update_matrix = false; kwargs...)
        x = copy(b) #
        ...
    end
end
```
This does not mutate the incoming `x`, so `linsolve!` simply doesn't do what it's supposed to. Furthermore, since this test is meant to ensure the solution doesn't change, it "passes" because `linsolve!` doesn't actually do what it's suppose to.

Since this depends on an older version of OrdinaryDiffEq, we think it's best to simply remove this test.

Co-authored-by: Charles Kawczynski <[email protected]>

.buildkite/pipeline.yml

@@ -804,15 +804,6 @@ steps:
         artifact_paths:
           - "examples/column/output/hydrostatic_discrete/*"
 
-      - label: ":computer: Column Hydrostatic Balance Eq - implicit"
-        key: "cpu_column_hydrostatic_implicit"
-        command:
-          - "julia --color=yes --project=examples examples/column/hydrostatic_implicit.jl"
-        artifact_paths:
-          - "examples/column/output/hydrostatic_implicit/*"
-        soft_fail:
-          - exit_status: 1
-
   - group: "Examples: Spectral element"
     steps:
       - label: ":computer: Bickley jet CG"