Make flush interval in telemetry configurable via sidecar

[cataphract]

Environment variables read via environ when sidecar is spawned are not necessarily available (see https://gist.github.com/cataphract/78ca7cabdded79360d790a8bc249e93d ). Add telemetry flush interval as a session config entry instead.

[pr-commenter]

Benchmarks

This comment was omitted because it was over 65536 characters.Please check the Gitlab Job logs to see its output.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 70.21%. Comparing base (ccc5efc) to head (2cca88b).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #527      +/-   ##
==========================================
- Coverage   70.22%   70.21%   -0.02%     
==========================================
  Files         206      206              
  Lines       27810    27815       +5     
==========================================
  Hits        19530    19530              
- Misses       8280     8285       +5     

Components	Coverage Δ
crashtracker	16.86% <ø> (ø)
datadog-alloc	98.73% <ø> (ø)
data-pipeline	51.15% <ø> (ø)
data-pipeline-ffi	0.00% <ø> (ø)
ddcommon	86.41% <ø> (ø)
ddcommon-ffi	75.31% <ø> (ø)
ddtelemetry	59.02% <ø> (ø)
ipc	84.13% <ø> (ø)
profiling	78.68% <ø> (ø)
profiling-ffi	58.26% <ø> (ø)
serverless	0.00% <ø> (ø)
sidecar	35.64% <0.00%> (-0.05%)	⬇️
sidecar-ffi	0.00% <0.00%> (ø)
spawn-worker	54.98% <ø> (ø)
trace-mini-agent	70.93% <ø> (ø)
trace-normalization	98.24% <ø> (ø)
trace-obfuscation	95.73% <ø> (ø)
trace-protobuf	77.16% <ø> (ø)
trace-utils	89.91% <ø> (ø)

[bwoebi]

Looks good :-)