[Metrics Kubernetes] Nodes: Fix memory usage by node

[constanca-m]

What does this PR do?

Fix the function to calculate pod memory usage.

Screenshots

Since, the total memory node used in the function was kubernetes.node.memory.allocatable.bytes, every memory used by system daemons was not being considered. Changing it to kubernetes.node.memory.capacity.bytes fix problems like the one mentioned in #4577.

Before:

After:

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• Start Time: 2022-12-02T14:09:17.526+0000

• Duration: 29 min 4 sec

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Total	91

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Name	Metrics % (covered/total)	Diff
Packages	100.0% (0/0)	💚
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Classes	100.0% (0/0)	💚
Methods	94.872% (74/78)	👎 -3.7
Lines	100.0% (0/0)	💚 6.171
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[tetianakravchenko]

could you please add a screenshot to the PR description that includes the changes in this PR, instead of the on with the issue?

[elasticmachine]

Package kubernetes - 1.29.2 containing this change is available at https://epr.elastic.co/search?package=kubernetes