[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:

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• Start Time: 2022-12-02T13:02:46.821+0000

• Duration: 30 min 37 sec

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Test	Results
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Passed	91
Skipped	0
Total	91

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[tetianakravchenko]

here seems to be quite some changes, that are not related to the initial issue, could you please double-check it?

[tetianakravchenko]

this change is not related to this PR, isn't it?

[constanca-m]

I was having trouble removing the parallel commit, so I had to create a new PR #4756 since the repo got deleted.

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🌐 Coverage report

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

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• Start Time: 2022-12-02T13:29:47.054+0000

• Duration: 29 min 34 sec

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Test	Results
Failed	0
Passed	91
Skipped	0
Total	91

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🌐 Coverage report

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

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• Start Time: 2022-12-02T13:32:57.077+0000

• Duration: 30 min 1 sec

Test stats 🧪

Test	Results
Failed	0
Passed	91
Skipped	0
Total	91

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🌐 Coverage report

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