Previously `Step` parameter would set a hard value for any zoom level.

Now it's renamed to `Min step` and sets the minimal value of `step` parameter
to Prometheus query. User would usually want to set it to the scraping interval
of the target metric to avoid having shap cliffs on graphs and extra load
on Prometheus. Actual `step` value is calculated as the minimum of automatically
selected step (based on zoom level) and user provided minimal step. If user
did not provide the step, then automatic value is used as is.

Example bahavior for `60s` scrape intervals:

* `5s` automatic interval, no user specified min step:
  * Before: `step=5`
  * After: `step=5`
* `5s` automatic interval, `1m` user specified min step:
  * Before: `step=5`
  * After: `step=60`
* `5m` automatic interval, `1m` user specified min step:
  * Before: `step=60` (not really visible, too dense)
  * After: `step=300` (automatic value is picked)

See:

* https://github.com/grafana/grafana/issues/8065
* https://github.com/prometheus/prometheus/issues/2564

Tab size was added as 2 in .editorconfig but a tab size of 4 is used
throughout go code base.

This can cause editors such as vscode to automatically reformat open .go
files to tab size 2 from 4.

plugins: refactoring builtIn data source concept, now means data source plugins that you do not need to add via data sources page, that is automatically added as selectable data source, #8095

Merge branch 'always_displayed_datasources' of https://github.com/ctide/grafana into ctide-always_displayed_datasources

org: fixed issue with orgId query param redirect handling when grafana is under subpath and reverse proxy, fixes #8089

* upgrade to aws-sdk-go v1.8.11

* fix test

Add alwaysDisplayed option to datasource plugins, this will allow it to show up as an option to select when adding queries to a panel without actually adding it as a datasource.

If grafana-server binary is started with the -profile flag then
tracing will create a trace.out file and pprof data can be accessed
on the 6060 port.

A custom port for pprof profiling can be set with the -profile-port
flag.

Collapse all ros -> Collapse all rows

* graph: initial histogram support #600

* graph histogram mode: add Bars number option

* graph histogram mode: fix X axis ticks calculation

* graph histogram mode: change bar style (align and width)

* refactor(graph): move histogram functions into separate module

* graph histogram mode: rename series to "count"

* graph histogram mode: fix errors if no data

* refactor(graph and heatmap): move shared code into app/core

* graph: add tests for histogram mode

* Fix restoration of ad-hoc variable value issue

* Escape delimiters in ad-hoc variable URL

* Remove unnecessary newline

* Add @ngInject to HeatmapCtrl constructor, issue #8013

* Remove unused loadPluginCss

This reverts commit 554f972a.

fix: sqlite3 and concurrent write requests caused database locked error some times, depending on how many concurrent requests and speed of disk drive. Fixed by reducign the number of concurrent db connections to 1 for sqlite3, fixes #7992