fix(otel_otlp_logs): encode log record body as string instead of int array

[javiergarea]

Description

Currently, log record bodies are encoded as integer arrays before exporting. This causes downstream log backends to render the logs as raw byte lists rather than human-readable text strings.
e.g.,

This change switches the regex replacement to use {return, binary}, ensuring the exporter generates a string_value.

Root cause

As seen in the shell output below, otel_otlp_common:to_any_value/1 converts a list string into an array_value of integers, while a binary becomes a string_value.

Erlang/OTP 28 [erts-16.1.1] [source] [64-bit] [smp:22:22] [ds:22:22:10] [async-threads:1] [jit:ns]

Eshell V16.1.1 (press Ctrl+G to abort, type help(). for help)
1> otel_otlp_common:to_any_value("test").
#{value =>
      {array_value,#{values =>
                         [#{value => {int_value,116}},
                          #{value => {int_value,101}},
                          #{value => {int_value,115}},
                          #{value => {int_value,116}}]}}}
2> otel_otlp_common:to_any_value(<<"test">>).
#{value => {string_value,<<"test">>}}

[tsloughter]

Thanks!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 17.66%. Comparing base (98be90e) to head (1cbcd98).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #952   +/-   ##
=======================================
  Coverage   17.66%   17.66%           
=======================================
  Files          24       24           
  Lines         719      719           
=======================================
  Hits          127      127           
  Misses        592      592           

Flag	Coverage Δ
api	17.66% <ø> (ø)
elixir	17.66% <ø> (ø)

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[javiergarea]

Amended commit scope from otel_otlp_logs to exporter to pass commit validation.
@tsloughter