Remove unused methods from `EntryStore`

[sandreae]

📋 Checklist

• [x] Add tests that cover your changes
• [x] Add this PR to the Unreleased section in CHANGELOG.md
• [x] Link this PR to any issues it closes
• [x] New files contain a SPDX license header

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.09% :warning:

Comparison is base (4a2c34c) 92.45% compared to head (367d021) 92.36%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #560 +/- ## ========================================== - Coverage 92.45% 92.36% -0.09% ========================================== Files 106 106 Lines 18039 17835 -204 ========================================== - Hits 16678 16474 -204 Misses 1361 1361 ``` | [Files Changed](https://app.codecov.io/gh/p2panda/aquadoggo/pull/560?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda) | Coverage Δ | | |---|---|---| | [aquadoggo/src/db/stores/entry.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/560?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9kYi9zdG9yZXMvZW50cnkucnM=) | `99.14% <ø> (-0.26%)` | :arrow_down: | | [aquadoggo/src/graphql/mutations/publish.rs](https://app.codecov.io/gh/p2panda/aquadoggo/pull/560?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda#diff-YXF1YWRvZ2dvL3NyYy9ncmFwaHFsL211dGF0aW9ucy9wdWJsaXNoLnJz) | `98.71% <100.00%> (ø)` | | ... and [3 files with indirect coverage changes](https://app.codecov.io/gh/p2panda/aquadoggo/pull/560/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=p2panda)

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