fix(core): Switch emitDistinctChangesOnlyDefaultValue to true

The previous implementation would fire changes `QueryList.changes.subscribe`
whenever the `QueryList` was recomputed. This resulted in an artificially
high number of change notifications, as it is possible that recomputing
`QueryList` results in the same list. When the `QueryList` gets recomputed
is an implementation detail, and it should not be the thing that determines
how often change event should fire.

Unfortunately, fixing the behavior outright caused too many existing
applications to fail. For this reason, Angular considers this fix a
breaking fix and has introduced a flag in `@ContentChildren` and
`@ViewChildren`, that controls the behavior.

```
export class QueryCompWithStrictChangeEmitParent {
  @ContentChildren('foo', {
    // This option will become the default in the future
    emitDistinctChangesOnly: true,
  })
  foos!: QueryList<any>;
}
```
For backward compatibility before v12
`emitDistinctChangesOnlyDefaultValue` was set to `false. This change
changes the default to `true`.

packages/compiler/src/core.ts

@@ -30,7 +30,7 @@ export const createAttribute =
 // Stores the default value of `emitDistinctChangesOnly` when the `emitDistinctChangesOnly` is not
 // explicitly set. This value will be changed to `true` in v12.
 // TODO(misko): switch the default in v12 to `true`. See: packages/core/src/metadata/di.ts
-export const emitDistinctChangesOnlyDefaultValue = false;
+export const emitDistinctChangesOnlyDefaultValue = true;
 
 
 export interface Query {

packages/core/src/metadata/di.ts

@@ -109,7 +109,7 @@ export interface Query {
 // Stores the default value of `emitDistinctChangesOnly` when the `emitDistinctChangesOnly` is not
 // explicitly set. This value will be changed to `true` in v12.
 // TODO(misko): switch the default in v12 to `true`. See: packages/compiler/src/core.ts
-export const emitDistinctChangesOnlyDefaultValue = false;
+export const emitDistinctChangesOnlyDefaultValue = true;
 
 
 /**