Backport of Fix handling of SignatureBits for ECDSA issuers into release/1.10.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #14943 to be assessed for backporting due to the inclusion of the label backport/1.10.x.

WARNING automatic cherry-pick of commits failed. Commits will require human attention.

The below text is copied from the body of the original PR.

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When adding SignatureBits control logic, we incorrectly allowed
specification of SignatureBits in the case of an ECDSA issuer. As noted
in the original request, NIST and Mozilla (and others) are fairly
prescriptive in the choice of signatures (matching the size of the
NIST P-curve), and we shouldn't usually use a smaller (or worse, larger
and truncate!) hash.

Ignore the configuration of signature bits and always use autodetection
for ECDSA like ed25519.

Signed-off-by: Alexander Scheel <alex.scheel@hashicorp.com>

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This definitely warrants a changelog entry, but not sure if we need anything else? This was added in 1.10.0, we'll backport this to 1.10.1, fixing the issue. It only presently works on roles (it should probably be added to the other endpoints later?).

Ticket: VAULT-5707

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[cipherboy]

Looks like I'll still have to do this one manually :/