Fix timeout 1200sec issue for large tensor tests

[ChaiBapchya]

Description

Large tensor tests on nightly fail due to timeout issue. Removing the timeout limit for these tests

@szha @leezu @access2rohit
@ciyongch I will cherrypick both the large tensor fixes [once this gets merged]

[mxnet-bot]

Hey @ChaiBapchya , Thanks for submitting the PR
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[ChaiBapchya]

http://jenkins.mxnet-ci.amazon-ml.com/blue/organizations/jenkins/nightly_chai/detail/fix_large_vector_nightly/1/pipeline/100

http://jenkins.mxnet-ci.amazon-ml.com/blue/organizations/jenkins/NightlyTestsForBinaries/detail/master/673/pipeline/100

[ChaiBapchya]

While this fix makes sure timeout doesn't happen, it results in few large tensor tests getting skip, few tests pass

test session starts ==============================

[2020-04-30T21:01:52.958Z] platform linux -- Python 3.5.2, pytest-5.3.5, py-1.8.1, pluggy-0.13.1

[2020-04-30T21:01:52.958Z] rootdir: /work/mxnet, inifile: pytest.ini

[2020-04-30T21:01:52.958Z] plugins: timeout-1.3.4, xdist-1.31.0, forked-1.1.3, env-0.6.2, cov-2.8.1

[2020-04-30T21:01:52.958Z] timeout: 1200.0s

[2020-04-30T21:01:52.958Z] timeout method: signal

[2020-04-30T21:01:52.958Z] timeout func_only: False

[2020-04-30T21:01:52.958Z] collected 1 item

[2020-04-30T21:01:52.958Z] 

[2020-04-30T21:05:14.349Z] tests/nightly/test_large_vector.py s                                     [100%]

[2020-04-30T21:05:14.349Z] 

[2020-04-30T21:05:14.349Z] ======================== 1 skipped in 188.48s (0:03:08) ========================

[2020-04-30T21:05:14.349Z] + pytest tests/nightly/test_large_vector.py::test_nn

[2020-04-30T21:05:14.349Z] ============================= test session starts ==============================

[2020-04-30T21:05:14.349Z] platform linux -- Python 3.5.2, pytest-5.3.5, py-1.8.1, pluggy-0.13.1

[2020-04-30T21:05:14.349Z] rootdir: /work/mxnet, inifile: pytest.ini

[2020-04-30T21:05:14.349Z] plugins: timeout-1.3.4, xdist-1.31.0, forked-1.1.3, env-0.6.2, cov-2.8.1

[2020-04-30T21:05:14.349Z] timeout: 1200.0s

[2020-04-30T21:05:14.349Z] timeout method: signal

[2020-04-30T21:05:14.349Z] timeout func_only: False

[2020-04-30T21:05:14.349Z] collected 1 item

[2020-04-30T21:05:14.349Z] 

[2020-04-30T21:53:21.695Z] tests/nightly/test_large_vector.py .                                     [100%]

[2020-04-30T21:53:21.695Z] 

[2020-04-30T21:53:21.695Z] ======================== 1 passed in 2898.25s (0:48:18) ========================

Here : http://jenkins.mxnet-ci.amazon-ml.com/blue/organizations/jenkins/NightlyTestsForBinaries/detail/master/675/pipeline/100

[ChaiBapchya]

It works as expected. The skip command in the test_large_vector.py is the cause.