Harvest should use HARVEST_CONF when set

[cgrinds]

The following steps should work

mv conf/ /tmp/
bin/poller --poller sar --promPort 12990
# poller fails to start because templates can't be found since conf directory was removed

# Starts fine with env var
HARVEST_CONF=/tmp/ bin/poller --poller sar --promPort 12990
2023-09-18T14:12:23-04:00 INF poller/poller.go:215 > Init Poller=sar asup=false confPath=conf config=harvest.yml configPath=/tmp/harvest.yml daemon=false debug=false homePath=/tmp hostname=cgrindst-mac-0 logLevel=info logPath=/var/log/harvest/ profiling=0 promPort=12990 version="harvest version 23.09.1814-v23.08.0 (commit c4646c8e) (build date 2023-09-18T14:11:27-0400) darwin/amd64"
2023-09-18T14:12:23-04:00 INF poller/poller.go:239 > started in foreground Poller=sar pid=67308
...
2023-09-18T14:12:23-04:00 INF poller/poller.go:366 > poller start-up complete Poller=sar
2023-09-18T14:12:23-04:00 INF prometheus/httpd.go:40 > server listen Poller=sar exporter=prometheus1 url=http://localhost:12990/metrics

[cgrinds]

Thanks to @ybizeul for reporting.

Fixed by:

• fix: read templates from HARVEST_CONF when set #2366
• fix: read harvest.yml from HARVEST_CONF when set #2367

[cgrinds]

Related #368

[rahulguptajss]

verified in main