Merge bitcoin/bitcoin#32406: policy: uncap datacarrier by default

a189d63618 add release note for datacarriersize default change (Greg Sanders)
a141e1bf50 Add more OP_RETURN mempool acceptance functional tests (Peter Todd)
0b4048c733 datacarrier: deprecate startup arguments for future removal (Greg Sanders)
63091b79e7 test: remove unnecessary -datacarriersize args from tests (Greg Sanders)
9f36962b07 policy: uncap datacarrier by default (Greg Sanders)

Pull request description:

  Retains the `-datacarrier*` args, marks them as deprecated, and does not require another startup argument for multiple OP_RETURN outputs.

  If a user has set `-datacarriersize` the value is "budgeted" across all seen OP_RETURN output scriptPubKeys. In other words the total script bytes stays the same, but can be spread across any number of outputs. This is done to not introduce an additional argument to support multiple outputs.

  I do not advise people use the option with custom arguments and it is marked as deprecated to not mislead as a promise to offer it forever. The argument itself can be removed in some future release to clean up the code and minimize footguns for users.

ACKs for top commit:
  stickies-v:
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  Sjors:
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  polespinasa:
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  hodlinator:
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  ajtowns:
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  mzumsande:
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  petertodd:
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  theStack:
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  1440000bytes:
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  willcl-ark:
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  dergoegge:
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  fanquake:
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  murchandamus:
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  darosior:
    Concept ACK a189d63618.

Tree-SHA512: 3da2f1ef2f50884d4da7e50df2121bf175cb826edaa14ba7c3068a6d5b2a70beb426edc55d50338ee1d9686b9f74fdf9e10d30fb26a023a718dd82fa1e77b038

doc/release-notes-32406.md

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+- `-datacarriersize` is increased to 100,000 which effectively uncaps the limit (as the maximum transaction size limit will be hit first). It can be overridden with -datacarriersize=83 to revert to the limit enforced in previous versions. Both `-datacarrier` and `-datacarriersize` options have been marked as deprecated and are expected to be removed in a future release. (#32406)
+
+- Multiple data carrier (OP_RETURN) outputs in a transaction are now permitted for relay and mining. The `-datacarriersize` limit applies to the aggregate size of the scriptPubKeys across all such outputs in a transaction, not including the scriptPubKey size itself. (#32406)