Speed up 11ty generation process for single pages

[devnook]

[devnook]

Things I tried so far:

• Generation of a single page using same environment as prod build = ~13s
• Same but on Cloud function instead of GAE = ~10s
• Use cloud storadge bucket for files instead of local filesystem = ~20s
• remove slow modules from _data and mark all .md files as .eleventyignore = ~3s

3s is on ok time for a preview server, however this result is highly variable (even outside of the colds start period). We need to:

• optimize further _data, both for prod and for preview
• dynamically generate .eleventyignore for preview server

[devnook]

More ideas:

• bump up node version to 16
• bump up instance_type to F4