prometheus: updated to 2.15.2

2.15.2:
[BUGFIX] TSDB: Fixed support for TSDB blocks built with Prometheus before 2.1.0.
[BUGFIX] TSDB: Fixed block compaction issues on Windows.

2.15.1:
[BUGFIX] Fixed race on concurrent queries against the same data.

2.15.0:
[CHANGE] Discovery: Removed prometheus_sd_kubernetes_cache_* metrics. Additionally prometheus_sd_kubernetes_workqueue_latency_seconds and prometheus_sd_kubernetes_workqueue_work_duration_seconds metrics now show correct values in seconds.
[CHANGE] Remote write: Changed query label on prometheus_remote_storage_* metrics to remote_name and url.
[FEATURE] API: Added new endpoint for exposing per metric metadata /metadata.
[ENHANCEMENT] TSDB: Significantly reduced memory footprint of loaded TSDB blocks.
[ENHANCEMENT] TSDB: Significantly optimized what we buffer during compaction which should result in lower memory footprint during compaction.
[ENHANCEMENT] TSDB: Improve replay latency.
[ENHANCEMENT] TSDB: WAL size is now used for size based retention calculation.
[ENHANCEMENT] Remote read: Added query grouping and range hints to the remote read request
[ENHANCEMENT] Remote write: Added prometheus_remote_storage_sent_bytes_total counter per queue.
[ENHANCEMENT] promql: Improved PromQL parser performance.
[ENHANCEMENT] React UI: Implemented missing pages like /targets
[ENHANCEMENT] promql: Prometheus now accepts spaces between time range and square bracket. e.g [ 5m]
[BUGFIX] Config: Fixed alertmanager configuration to not miss targets when configurations are similar.
[BUGFIX] Remote write: Value of prometheus_remote_storage_shards_desired gauge shows raw value of desired shards and it's updated correctly.
[BUGFIX] Rules: Prometheus now fails the evaluation of rules and alerts where metric results collide with labels specified in labels field.
[BUGFIX] API: Targets Metadata API /targets/metadata now accepts empty match_targets parameter as in the spec.

(adam)