config-loader: make MergedConfigSource internal

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/config-loader/src/sources/MergedConfigSource.ts

@@ -25,6 +25,7 @@ const sourcesSymbol = Symbol.for(
   '@backstage/config-loader#MergedConfigSource.sources',
 );
 
+/** @internal */
 export class MergedConfigSource implements ConfigSource {
   // An optimization to flatten nested merged sources to avid unnecessary microtasks
   static #flattenSources(sources: ConfigSource[]): ConfigSource[] {

packages/config-loader/src/sources/index.ts

@@ -18,7 +18,6 @@ export { ConfigSources } from './ConfigSources';
 export { EnvConfigSource, readEnvConfig } from './EnvConfigSource';
 export { FileConfigSource } from './FileConfigSource';
 export type { FileConfigSourceOptions } from './FileConfigSource';
-export { MergedConfigSource } from './MergedConfigSource';
 export { MutableConfigSource } from './MutableConfigSource';
 export { RemoteConfigSource } from './RemoteConfigSource';
 export type { RemoteConfigSourceOptions } from './RemoteConfigSource';