Plugins: Support for distributed tracing in backend plugins SDK (#63714)

* Tracing: Pass OTLP address and propagation format to plugins

* Fix unit tests

* Fix indentation

* Fix plugin manager integration tests

* Goimports

* Pass plugin version to plugins

* Do not add GF_PLUGIN_VERSION if plugin version is not set, add tests

* Allow disabling plugins distributed tracing on a per-plugin basis

* Moved disabled plugins to tracing.opentelemetry config section

* Pre-allocate DisabledPlugins map to the correct size

* Moved disable tracing setting flags in plugin settings

* Renamed plugin env vars for tracing endpoint and propagation

* Fix plugin initializer tests

* Refactoring: Moved OpentelemetryCfg from pkg/infra to pkg/plugins

* Changed GetSection to Section in parseSettingsOpentelemetry

* Add tests for NewOpentelemetryCfg

* Fix test case names in TestNewOpentelemetryCfg

* OpenTelemetry: Remove redundant error checks

pkg/plugins/config/tracing.go

@@ -0,0 +1,38 @@
+package config
+
+import (
+	"fmt"
+
+	"github.com/grafana/grafana/pkg/infra/tracing"
+	"github.com/grafana/grafana/pkg/setting"
+)
+
+const otlpExporter string = "otlp"
+
+// OpentelemetryCfg contains the Opentelemetry address and propagation config values.
+// This is used to export the Opentelemetry (OTLP) config without exposing the whole *setting.Cfg.
+type OpentelemetryCfg struct {
+	Address     string
+	Propagation string
+}
+
+// IsEnabled returns true if OTLP tracing is enabled (address set)
+func (c OpentelemetryCfg) IsEnabled() bool {
+	return c.Address != ""
+}
+
+// NewOpentelemetryCfg creates a new OpentelemetryCfg based on the provided Grafana config.
+// If Opentelemetry (OTLP) is disabled, a zero-value OpentelemetryCfg is returned.
+func NewOpentelemetryCfg(grafanaCfg *setting.Cfg) (OpentelemetryCfg, error) {
+	ots, err := tracing.ParseSettingsOpentelemetry(grafanaCfg)
+	if err != nil {
+		return OpentelemetryCfg{}, fmt.Errorf("parse settings: %w", err)
+	}
+	if ots.Enabled != otlpExporter {
+		return OpentelemetryCfg{}, nil
+	}
+	return OpentelemetryCfg{
+		Address:     ots.Address,
+		Propagation: ots.Propagation,
+	}, nil
+}