chore(test): disable config clearing by default

The call to `this.clearConfig()` in `Garden#scanAndAddConfigs` had
started breaking certain test cases that manually set action configs
before calling `garden.getConfigGraph` (which would scan and add
configs, thus discarding the manually set configs).

While it's not great that we're adding more tweaks to the `TestGarden`
class, we're almost never interested in explicitly testing the post-edit
config reloading (outside of tests that test interactive / dev command
funcftionality).

core/src/garden.ts

@@ -1287,7 +1287,7 @@ export class Garden {
    * We need to clear before rescanning to make sure old/outdated configs are cleared away, and to avoid duplicate
    * key errors when adding the newly scanned ones (and those generated from newly scanned config templates).
    */
-  private clearConfigs() {
+  protected clearConfigs() {
     for (const kind of Object.getOwnPropertyNames(this.actionConfigs)) {
       clearObject(this.actionConfigs[kind])
     }

core/src/util/testing.ts

@@ -165,6 +165,7 @@ export type TestGardenOpts = Partial<GardenOpts> & {
   noTempDir?: boolean
   onlySpecifiedPlugins?: boolean
   remoteContainerAuth?: boolean
+  clearConfigsOnScan?: boolean
 }
 
 export class TestGarden extends Garden {
@@ -179,6 +180,7 @@ export class TestGarden extends Garden {
   public declare variables: DeepPrimitiveMap
   private repoRoot!: string
   public cacheKey!: string
+  public clearConfigsOnScan = false
 
   constructor(params: GardenParams) {
     super(params)
@@ -228,6 +230,14 @@ export class TestGarden extends Garden {
     return garden
   }
 
+  protected override clearConfigs() {
+    if (this.clearConfigsOnScan) {
+      super.clearConfigs()
+    } else {
+      // No-op: We need to disable this method, because it breaks test cases that manually set configs.
+    }
+  }
+
   override async processTasks(params: Omit<SolveParams, "log"> & { log?: Log }) {
     return super.processTasks({ ...params, log: params.log || this.log })
   }

core/test/unit/src/commands/base.ts

@@ -226,6 +226,9 @@ describe("Command", () => {
 
       it("passes on changed configs and templates to the parent and subsequent child instances", async () => {
         const garden = await makeTestGarden(projectRoot)
+        // Here, we're testing the config clearing logic, so we turn this behavior on (which is off by default for
+        // TestGarden instances).
+        garden.clearConfigsOnScan = true
         // `makeTestGarden` does some trickery to copy the project root into a temp directory and work from there
         // (which is nice, since it avoids the need for cleanup).
         // Therefore, we need to make our find & replace substitutions inside the temp dir here.