build: upgrade to go 1.19 (#25726)

This changes the CI / release builds to use the latest Go version. It also
upgrades golangci-lint to a newer version compatible with Go 1.19.

In Go 1.19, godoc has gained official support for links and lists. The
syntax for code blocks in doc comments has changed and now requires a
leading tab character. gofmt adapts comments to the new syntax
automatically, so there are a lot of comment re-formatting changes in this
PR. We need to apply the new format in order to pass the CI lint stage with
Go 1.19.

With the linter upgrade, I have decided to disable 'gosec' - it produces
too many false-positive warnings. The 'deadcode' and 'varcheck' linters
have also been removed because golangci-lint warns about them being
unmaintained. 'unused' provides similar coverage and we already have it
enabled, so we don't lose much with this change.

eth/downloader/downloader.go

@@ -741,9 +741,11 @@ func (d *Downloader) fetchHead(p *peerConnection) (head *types.Header, pivot *ty
 // calculateRequestSpan calculates what headers to request from a peer when trying to determine the
 // common ancestor.
 // It returns parameters to be used for peer.RequestHeadersByNumber:
-//  from - starting block number
-//  count - number of headers to request
-//  skip - number of headers to skip
+//
+//	from  - starting block number
+//	count - number of headers to request
+//	skip  - number of headers to skip
+//
 // and also returns 'max', the last block which is expected to be returned by the remote peers,
 // given the (from,count,skip)
 func calculateRequestSpan(remoteHeight, localHeight uint64) (int64, int, int, uint64) {

eth/downloader/queue.go

@@ -480,9 +480,10 @@ func (q *queue) ReserveReceipts(p *peerConnection, count int) (*fetchRequest, bo
 // to access the queue, so they already need a lock anyway.
 //
 // Returns:
-//   item     - the fetchRequest
-//   progress - whether any progress was made
-//   throttle - if the caller should throttle for a while
+//
+//	item     - the fetchRequest
+//	progress - whether any progress was made
+//	throttle - if the caller should throttle for a while
 func (q *queue) reserveHeaders(p *peerConnection, count int, taskPool map[common.Hash]*types.Header, taskQueue *prque.Prque,
 	pendPool map[string]*fetchRequest, kind uint) (*fetchRequest, bool, bool) {
 	// Short circuit if the pool has been depleted, or if the peer's already

eth/downloader/resultstore.go

@@ -71,10 +71,11 @@ func (r *resultStore) SetThrottleThreshold(threshold uint64) uint64 {
 // wants to reserve headers for fetching.
 //
 // It returns the following:
-//   stale     - if true, this item is already passed, and should not be requested again
-//   throttled - if true, the store is at capacity, this particular header is not prio now
-//   item      - the result to store data into
-//   err       - any error that occurred
+//
+//	stale     - if true, this item is already passed, and should not be requested again
+//	throttled - if true, the store is at capacity, this particular header is not prio now
+//	item      - the result to store data into
+//	err       - any error that occurred
 func (r *resultStore) AddFetch(header *types.Header, fastSync bool) (stale, throttled bool, item *fetchResult, err error) {
 	r.lock.Lock()
 	defer r.lock.Unlock()