Update CWAOperator default tolerations and CWA/FluentBit default PriorityClass

[sky333999]

Issue #, if available: #54, aws/containers-roadmap#2462

Description of changes:

• Default tolerations are mainly applicable for daemonsets deployed by the helm-chart / EKS add-on such as CloudWatchAgent and FluentBit. These should not apply to the CloudWatchAgentOperator deployment by default as this impacts scenarios such as a node draining.
• feat(fluent-bit): set system-node-critical as a default priorityClass #70 introduced the ability to set the PriorityClass for the CloudWatchAgent and the FluentBit daemonsets, but set the default to "". Given observability agents are critical to the health of a cluster, this change updates these to run as "system-node-critical" by default.

Both of these changes will be included in the next major version bump of the helm-chart / EKS add-on.

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