Drop support for `xerrors`

[darccio]

Discussed in #4300

^{Originally posted by darccio December 19, 2025}

Package Name

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Package Version(s)

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Describe the feature you'd like

golang.org/x/xerrors dependency that is no longer maintained but still included in dd-trace-go.

Is your feature request related to a problem?

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Describe alternatives you've considered

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Additional context

Relates to #4176