Unbounded HTTP response body read in OpenTelemetry.Sampler.AWS

The AWS X-Ray Remote Sampler package provides a sampler which can get sampling configurations from AWS X-Ray. Prior to 0.1.0-alpha.8, OpenTelemetry.Sampler.AWS reads unbounded HTTP response bodies from a configured AWS X-Ray remote sampling endpoint into memory. AWSXRaySamplerClient.DoRequestAsync called HttpClient.SendAsync followed by ReadAsStringAsync(), which materializes the entire HTTP response body into a single in-memory string with no size limit. The sampling endpoint is configurable via AWSXRayRemoteSamplerBuilder.SetEndpoint (default: http://localhost:2000). An attacker who controls the configured endpoint, or who can intercept traffic to it (MitM), can return an arbitrarily large response body. This causes unbounded heap allocation in the consuming process, leading to high transient memory pressure, garbage-collection stalls, or an OutOfMemoryException that terminates the process. This vulnerability is fixed in 0.1.0-alpha.8.