Fix verify_size w/ verify_hash set to true in VerifyStore

[allada]

Fixes bug where verify_size & verify_hash are both set to true, it'd cause small messages to always fail the hash check.

fixes #1272

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This change is 

[allada]

Reviewable status: 0 of 1 LGTMs obtained, and 0 of 2 files reviewed, and pending CI: Analyze (javascript-typescript), Analyze (python), Bazel Dev / ubuntu-22.04, Cargo Dev / macos-13, Cargo Dev / ubuntu-22.04, Installation / macos-13, Installation / macos-14, Installation / ubuntu-22.04, Local / ubuntu-22.04, Publish image, Publish nativelink-worker-init, Publish nativelink-worker-lre-cc, Remote / large-ubuntu-22.04, asan / ubuntu-22.04, docker-compose-compiles-nativelink (22.04), integration-tests (22.04), macos-13, pre-commit-checks, ubuntu-20.04 / stable, ubuntu-22.04, ubuntu-22.04 / stable, vale, windows-2022 / stable, and 1 discussions need to be resolved

a discussion (no related file):
Proof this test catches the failure presented:

failures:

---- verify_size_and_hash_suceeds_on_small_data stdout ----
thread 'verify_size_and_hash_suceeds_on_small_data' panicked at nativelink-store/tests/verify_store_test.rs:374:5:
assertion failed: `(left == right)`: Expected success, got: Err(Error { code: Internal, messages: ["Sender dropped before sending EOF", "During first read of buf_channel::take()", "Failed to collect all bytes from reader in memory_store::update", "---", "Hashes do not match, got: a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3 but digest hash was e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"] })

Diff < left / right > :
<Err(
<    Error {
<        code: Internal,
<        messages: [
<            "Sender dropped before sending EOF",
<            "During first read of buf_channel::take()",
<            "Failed to collect all bytes from reader in memory_store::update",
<            "---",
<            "Hashes do not match, got: a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3 but digest hash was e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
<        ],
<    },
>Ok(
>    (),
 )

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[allada]

+@adam-singer

Reviewable status: 0 of 1 LGTMs obtained, and 0 of 2 files reviewed, and pending CI: Analyze (javascript-typescript), Analyze (python), Bazel Dev / ubuntu-22.04, Cargo Dev / macos-13, Cargo Dev / ubuntu-22.04, Installation / macos-13, Installation / macos-14, Installation / ubuntu-22.04, Local / ubuntu-22.04, Publish image, Publish nativelink-worker-init, Publish nativelink-worker-lre-cc, Remote / large-ubuntu-22.04, asan / ubuntu-22.04, docker-compose-compiles-nativelink (22.04), integration-tests (22.04), macos-13, pre-commit-checks, ubuntu-20.04 / stable, ubuntu-22.04, ubuntu-22.04 / stable, vale, windows-2022 / stable, and 1 discussions need to be resolved (waiting on @adam-singer)

[adam-singer]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: 1 of 1 LGTMs obtained, and all files reviewed, and 1 discussions need to be resolved