Add: parameter on trim_conandata to block the raise an exception when conandata.yml file doesn't exist

[ErniGH]

Changelog: Feature: Add a parameter to trim_conandata to avoid raising an exception when conandata.yml file doesn't exist.
Docs: conan-io/docs#3624

Close: #15672

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[memsharded]

Implementation LGTM, and I'd say the default is also what I'd thought, but lets make sure we align on that.