Remove unused QueryBuilderService (#2104)

**Issue number:** #2068 

**What:**
- removed unused query-builder service files
  - medusa/src/services/query-builder.js
  - medusa/src/services/__mocks__/query-builder.js
- deleted export from medusa/src/services/index.ts
- (extra) deleted documentation files related to QueryBuilderService (QueryBuilderService.md)

docs/content/references/services/classes/QueryBuilderService.md

@@ -1,79 +0,0 @@
-# Class: QueryBuilderService
-
-## Hierarchy
-
-- `"medusa-interfaces"`
-
-  ↳ **`QueryBuilderService`**
-
-## Constructors
-
-### constructor
-
-• **new QueryBuilderService**()
-
-#### Inherited from
-
-BaseService.constructor
-
-## Methods
-
-### buildFilterQuery
-
-▸ **buildFilterQuery**(`filters`): `undefined` \| {}
-
-#### Parameters
-
-| Name | Type |
-| :------ | :------ |
-| `filters` | `any` |
-
-#### Returns
-
-`undefined` \| {}
-
-#### Defined in
-
-[packages/medusa/src/services/query-builder.js:25](https://github.com/medusajs/medusa/blob/f7a63f178/packages/medusa/src/services/query-builder.js#L25)
-
-___
-
-### buildQuery
-
-▸ **buildQuery**(`params`, `properties`): `Object`
-
-#### Parameters
-
-| Name | Type |
-| :------ | :------ |
-| `params` | `any` |
-| `properties` | `any` |
-
-#### Returns
-
-`Object`
-
-#### Defined in
-
-[packages/medusa/src/services/query-builder.js:5](https://github.com/medusajs/medusa/blob/f7a63f178/packages/medusa/src/services/query-builder.js#L5)
-
-___
-
-### buildTextSearchQuery
-
-▸ **buildTextSearchQuery**(`search`, `searchProperties`): `undefined` \| { `$or`: `any` = searchQuery }
-
-#### Parameters
-
-| Name | Type |
-| :------ | :------ |
-| `search` | `any` |
-| `searchProperties` | `any` |
-
-#### Returns
-
-`undefined` \| { `$or`: `any` = searchQuery }
-
-#### Defined in
-
-[packages/medusa/src/services/query-builder.js:39](https://github.com/medusajs/medusa/blob/f7a63f178/packages/medusa/src/services/query-builder.js#L39)

docs/content/references/services/index.md

@@ -30,7 +30,6 @@
 - [ProductService](classes/ProductService.md)
 - [ProductTypeService](classes/ProductTypeService.md)
 - [ProductVariantService](classes/ProductVariantService.md)
-- [QueryBuilderService](classes/QueryBuilderService.md)
 - [RegionService](classes/RegionService.md)
 - [ReturnReasonService](classes/ReturnReasonService.md)
 - [ReturnService](classes/ReturnService.md)