[chore] use mdatagen to generate service metrics (open-telemetry#10160)

This PR follows
open-telemetry#10159 and
uses the new mdatagen functionality to generate async metrics in the
service.

---------

Signed-off-by: Alex Boten <223565+codeboten@users.noreply.github.com>

service/documentation.md

@@ -0,0 +1,55 @@
+[comment]: <> (Code generated by mdatagen. DO NOT EDIT.)
+
+# service
+
+## Internal Telemetry
+
+The following telemetry is emitted by this component.
+
+### process_cpu_seconds
+
+Total CPU user and system time in seconds
+
+| Unit | Metric Type | Value Type | Monotonic |
+| ---- | ----------- | ---------- | --------- |
+| s | Sum | Double | true |
+
+### process_memory_rss
+
+Total physical memory (resident set size)
+
+| Unit | Metric Type | Value Type |
+| ---- | ----------- | ---------- |
+| By | Gauge | Int |
+
+### process_runtime_heap_alloc_bytes
+
+Bytes of allocated heap objects (see 'go doc runtime.MemStats.HeapAlloc')
+
+| Unit | Metric Type | Value Type |
+| ---- | ----------- | ---------- |
+| By | Gauge | Int |
+
+### process_runtime_total_alloc_bytes
+
+Cumulative bytes allocated for heap objects (see 'go doc runtime.MemStats.TotalAlloc')
+
+| Unit | Metric Type | Value Type | Monotonic |
+| ---- | ----------- | ---------- | --------- |
+| By | Sum | Int | true |
+
+### process_runtime_total_sys_memory_bytes
+
+Total bytes of memory obtained from the OS (see 'go doc runtime.MemStats.Sys')
+
+| Unit | Metric Type | Value Type |
+| ---- | ----------- | ---------- |
+| By | Gauge | Int |
+
+### process_uptime
+
+Uptime of the process
+
+| Unit | Metric Type | Value Type | Monotonic |
+| ---- | ----------- | ---------- | --------- |
+| s | Sum | Double | true |