Skip tensor tests by default in conda recipe to avoid OOM

[vlad-perevezentsev]

Tensor tests require significant device memory and frequently cause OOM crashes on internal CI machines during conda package testing (mostly on Linux) often manifesting as Python abort signals instead of regular failures.

This PR sets SKIP_TENSOR_TESTS=1 by default in conda recipe test scripts to avoid such crashes.

Users or CI environments can opt in by setting SKIP_TENSOR_TESTS=0 on systems with sufficient memory.

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/pull/2860/index.html

[antonwolfy]

I think it'd clear to mention explicit conda build --test ... command which is only affected. And also we need to state how it's possible to disable default behavior with setting env variable SKIP_TENSOR_TESTS=0 while running conda build --test ....

[vlad-perevezentsev]

Suggested change

	* Disabled `dpnp.tensor` tests by default in conda recipe to prevent OOM failures during package testing [#2859](https://github.com/IntelPython/dpnp/pull/2859)
	* Disabled `dpnp.tensor` tests by default in conda recipe to prevent OOM failures during package testing [#2860](https://github.com/IntelPython/dpnp/pull/2860)

[github-actions]

Array API standard conformance tests for dpnp=0.20.0dev6=py313h509198e_60 ran successfully.
Passed: 1357
Failed: 3
Skipped: 16