community[minor]: import fix (#20995)

Issue: When the third-party package is not installed, whenever we need
to `pip install <package>` the ImportError is raised.
But sometimes, the `ValueError` or `ModuleNotFoundError` is raised. It
is bad for consistency.
Change: replaced the `ValueError` or `ModuleNotFoundError` with
`ImportError` when we raise an error with the `pip install <package>`
message.
Note: Ideally, we replace all `try: import... except... raise ... `with
helper functions like `import_aim` or just use the existing
[langchain_core.utils.utils.guard_import](https://api.python.langchain.com/en/latest/utils/langchain_core.utils.utils.guard_import.html#langchain_core.utils.utils.guard_import)
But it would be much bigger refactoring. @baskaryan Please, advice on
this.

libs/community/langchain_community/document_loaders/pdf.py

@@ -634,7 +634,7 @@ class AmazonTextractPDFLoader(BasePDFLoader):
         try:
             import textractcaller as tc  # noqa: F401
         except ImportError:
-            raise ModuleNotFoundError(
+            raise ImportError(
                 "Could not import amazon-textract-caller python package. "
                 "Please install it with `pip install amazon-textract-caller`."
             )
@@ -662,7 +662,7 @@ class AmazonTextractPDFLoader(BasePDFLoader):
                 client = session.client("textract", **client_params)
 
             except ImportError:
-                raise ModuleNotFoundError(
+                raise ImportError(
                     "Could not import boto3 python package. "
                     "Please install it with `pip install boto3`."
                 )
@@ -710,7 +710,7 @@ class AmazonTextractPDFLoader(BasePDFLoader):
             from PIL import Image, ImageSequence
 
         except ImportError:
-            raise ModuleNotFoundError(
+            raise ImportError(
                 "Could not import pypdf or Pilloe python package. "
                 "Please install it with `pip install pypdf Pillow`."
             )