Change raise e from e calls to be just raise and remove unneeded ones

[bcalvert-graft]

Description

As per the discussion from #2221, the pattern,

try:
    <do something that might raise Exception>
except ExceptionType as exc
    <maybe do some additional stuff here>
    raise exc from exc

can break downstream tooling that seeks to unroll exc.__cause__ (e.g. for processing the stack trace).

This PR tweaks all spots in the pymilvus codebase that were using that pattern to instead either just use this pattern

try:
    <do something that might raise Exception>
except ExceptionType as exc
    <maybe do some additional stuff here>
    raise

or, if the try/except didn't have any additional logic in the except block, I removed the try/except entirely as a direct reraise would be redundant in those cases.

NB As mentioned in #2221, I originally only noticed three spots where the raise err from err pattern was used. While working on this PR I found a number of others and I ended up changing all of them. As per @XuanYang-cn's comment, if there are important reasons for one or more of these spots to stay as-is, please let me know and I can revert the changes to that section accordingly.

Testing

Finding all the spots

To find all the spots, I ran this grep

$ grep "raise \(.*\) from \1" pymilvus/**/*.py 

On master branch, we get a non-zero number of hits with the expected pattern. On the branch for this PR, the grep returns no values

Testing the fix

In one process, run

In [1]: from milvus_lite.server import Server

In [2]: s = Server('test.db', '127.0.0.1:9999')

In [3]: s.start()
Out[3]: True

In [4]: s._p.wait()

In another process, run

In [1]: import pymilvus

In [2]: client = pymilvus.MilvusClient("http://localhost:9999")
   ...: collection_name = "fake_embeddings"
   ...: if client.has_collection(collection_name=collection_name):
   ...:     client.drop_collection(collection_name=collection_name)
   ...: 

In [3]: vector_dim = 512
   ...: client.create_collection(
   ...:     collection_name=collection_name,
   ...:     vector_field_name="vector",
   ...:     dimension=vector_dim,
   ...:     auto_id=True,
   ...:     enable_dynamic_field=True,
   ...:     metric_type="COSINE",
   ...: )

In [4]: import numpy as np

In [5]: vectors = np.random.normal(loc=0, scale=1, size=(vector_dim + 2,))

In [6]: try:
   ...:     client.insert(collection_name, {"vector": vectors})
   ...: except pymilvus.MilvusException as exc:
   ...:     assert exc.__cause__ is not exc, "Exception is its own cause"

The In [6]: step will not through an AssertionError

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[sre-ci-robot]

Welcome @bcalvert-graft! It looks like this is your first PR to milvus-io/pymilvus 🎉