Issue warning about allowed_urls when default value is used

[namannandan]

Description

Issue warning about allowed_urls when default value is used.
The default value is file://.*|http(s)?://.*

Fixes #2531

Feature/Issue validation/testing

• Without allowed_urls configured

$ torchserve --ncs --start --model-store model_store                                     
$ WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact performance.
2023-08-22T11:29:05,267 [WARN ] main org.pytorch.serve.util.ConfigManager - Your torchserve instance can access any URL to load models. When deploying to production, make sure to limit the set of allowed_urls in config.properties
2023-08-22T11:29:05,271 [INFO ] main org.pytorch.serve.servingsdk.impl.PluginsManager - Initializing plugins manager...
..........

• With allowed_urls configured

$ cat custom_config.properties                                                           
allowed_urls="https://torchserve.pytorch.org/mar_files/.*"
$ torchserve --ncs --start --model-store model_store --ts-config custom_config.properties
$ WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact performance.
2023-08-22T11:31:58,644 [INFO ] main org.pytorch.serve.servingsdk.impl.PluginsManager - Initializing plugins manager...

[codecov]

Codecov Report

Merging #2534 (e5c3c99) into master (58eb2d2) will increase coverage by 0.08%.
The diff coverage is n/a.

❗ Current head e5c3c99 differs from pull request most recent head 391bdec. Consider uploading reports for the commit 391bdec to get more accurate results

@@            Coverage Diff             @@
##           master    #2534      +/-   ##
==========================================
+ Coverage   72.77%   72.85%   +0.08%     
==========================================
  Files          78       78              
  Lines        3695     3695              
  Branches       58       58              
==========================================
+ Hits         2689     2692       +3     
+ Misses       1002      999       -3     
  Partials        4        4              

see 1 file with indirect coverage changes

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