Wasmtime: omit ANSI color sequences in logging when not a terminal. #7436
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In #7239 we added a
tracing-log
subscriber that prints logs to stderr if enabled with an environment variable. It included logic to add ANSI color sequences when stderr is a terminal, for legibility. Unfortunately it seems that while this logic enabled colors on a terminal, it did not disable colors on a non-terminal; so redirects of stderr to a file would result in ANSI color sequences being captured in that file. Specifically, the builder seems not to default to no-color; so rather than enable-or-nothing, we should explicitly enable or disable always.Fixes #7435.