profiles: drop gzip requirement (#661)

There is no need for us to specifiy compression requirements on
OpenTelemetry profiles. This should be defined by OTLP, see [spec].

For #629

[spec]: https://opentelemetry.io/docs/specs/otlp/#protocol-details

Co-authored-by: Tigran Najaryan <[email protected]>

Author: felixge

opentelemetry/proto/profiles/v1development/profiles.proto

@@ -192,8 +192,6 @@ message ScopeProfiles {
 //   that is most useful to humans.  There should be enough
 //   information present to determine the original sampled values.
 //
-// - On-disk, the serialized proto must be gzip-compressed.
-//
 // - The profile is represented as a set of samples, where each sample
 //   references a sequence of locations, and where each location belongs
 //   to a mapping.